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LIPPINCOTT'S 
FARM  LIFE  TEXT  SERIES 

EDITED  BY 

KARY  C.  DAVIS,  Ph.D.  (Cornell) 

Applied 
Economic  Botany 


LIPPINCOTT'S 

FARM  MANUALS 

Edited  by  K.  C.  DAVIS.  Ph.D. 

SECOND   EDITION  REVISED 

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2  I 


ffl   "3 


Farm  Life  Text  Series 

EDITED  BY  K.  C.  DAVIS,  Ph.D.  (Cornkll) 


APPLIED 
ECONOMIC  BOTANY 

BASED   UPON  ACTUAL 

AGRICULTURAL    AND    GARDENING 

PROJECTS 


BY 

MELVILLE  THURSTON  COOK,  Ph.D. 

RUTGERS  COLLEGE,    NEW    BRUNSWICK,    N.    J. 


14s  ILLUSTRATIONS 


PHILADELPHIA  AND  LONDON 
J.  B.  LIPPINCOTT  COMPANY 


COPYRIGHT,    I919,    BY   J,    B.    LIPPINCOTT    COMPANY 


Electrotyped  and  printed  by  J.  B.  LippincoU  Company 
The  Washington  Square  Press,  Philadelphia,  U.S.A. 


PREFACE 

There  are  already  so  many  text-books  on  botany  that  the 
anthor  has  long  hesitated  to  present  another  to  the  educational 
public.  The  study  of  botany  has  developed  very  rapidly  in  the 
past  quarter  of  a  century  and  as  a  result  we  have  a  gi-eat  variety 
of  text-books  representing  an  almost  equally  great  variety  of 
methods  of  presenting  the  subject.  Yet,  we  meet  with  a  con- 
tinuous series  of  complaints  against  the  poorly  adapted  sec- 
ondary text-books  for  teaching  in  secondary  schools,  technical 
schools  and  colleges.  The  teacher  in  the  secondary  school  says 
that  text-books  are  written  by  college  professors  who  do  not 
understand  the  problems  involved  in  secondary  education ;  the 
teacher  in  the  technical  school  complains  because  the  students 
from  the  secondary  schools  cannot  correlate  the  botany  with 
related  subjects;  the  college  professors  complain  because  of  the 
mechanical  methods  used  in  the  secondary  schools  which  dis- 
courage rather  than  encourage  further  study  of  the  subject  by 
those  who  enter  college. 

Having  sei-ved  for  a  time  as  a  high-school  teacher,  the  author 
has  some  realization  of  the  difficulties  of  the  secondary  schools. 
As  a  college  professor  he  has  some  appreciation  of  the  keen  dis- 
appointment felt  by  those  who  conduct  the  Freshman  entrance 
examinations,  and  who  try  to  teach  botany  to  the  college  students 
that  come  to  college  with  ideas  of  botany  obtained  from  their 
training  in  the  secondary  schools.  By  experience,  he  has  learned 
that  the  results  of  the  entrance  examinations  are  fully  as  un- 
satisfactory when  the  questions  are  prepared  by  the  high-school 
teachers  as  when  prepared  by  himself. 

The  placing  of  the  responsibility  for  this  condition   is  a 


c 


vi  PREFACE 

problem  not  easily  solved.  But  the  writer  is  inclined  to  believe 
that  the  secondary  school  is  trying  to  do  too  much,  trying  to  do 
work  beyond  the  pupils,  trying  to  do  work  that  should  be  left 
for  the  college.  We  give  the  pupils  compound  microscopes, 
which  is  much  like  giving  them  a  complete  set  of  surveying 
instruments  for  use  in  the  study  of  elementary  arithmetic.  We 
try  to  teach  facts  when  we  should  teach  fundamental  principles, 
close  observation  and  accuracy.  We  try  to  teach  scientific  names 
when  we  should  teach  simple  methods  of  experimental  work. 

In  this  little  work  the  autlior  has  aimed  at  three  things, 
viz.:  (1)  A  brief  statement  of  the  recognized  facts  and  prin- 
ciples concerning  jjlants  and  plant  growth  usually  given  in  text- 
books for  secondary  schools.  (2)  A  list  of  simple  exercises  and 
suggestions  for  observations  which  the  pupil  can  conduct  with- 
out great  difficulty  and  which  will  demonstrate  many  of  the 
statements  given  in  the  book.  (  3 )  A  list  of  questions  which  are 
intended  to  be  suggestive  to  the  pupils  and  to  encourage  further 
studies. 

The  title,  "  Applied  Economic  Botany,"  implies  first,  that 
it  is  intended  as  a  guide  to  experimental  work  in  the  study 
of  plants,  such  as  should  be  carried  on  in  any  high  school, 
and  second,  that  it  is  intended  as  a  preliminary  work  to  the 
agricultural  studies  which  are  now  recognized  in  many  high 
schools. 

The  author  has  endeavored  to  make  the  work  so  flexible 
that  it  may  be  used  in  schools  regardless  of  the  amount  of  time 
devoted  to  the  subject,  the  available  laboratory  space  and  equip- 
ment. The  author  has  also  been  mindful  of  the  fact  that  the 
course  in  botany  in  the  secondary  school  should  meet  the  needs 
of  very  different  classes  of  pupils — those  who  study  it  as  one 
of  the  requirements  of  the  curriculum  and  to  whom  it  must  be 
primarily  a  cultural  subject,  those  who  study  it  as  a  prepara- 
tion to  agriculture  and  horticulture,  and  those  who  may  use  it 


PREFACE  vii 

to  fiillill  one  of  the  college  entrance  requirements.  The  same 
course  can  and  should  serve  all  of  these  purposes  in  the  same 
manner  that  the  courses  in  mathematics  and  Eng-lish  literature 
serve  those  who  go  direct  from  the  secondary  schools  into  the 
trades,  or  business  houses,  or  professions,  or  to  college. 

The  manuscript  has  been  submitted  to  both  high-school 
teachers  and  college  professors  for  criticisms  and  suggestions 
and  manj  changes  have  been  made  in  an  effort  to  meet  the 
requirements  of  both  classes  of  teachers,  although  the  general 
plan  of  the  work  has  not  been  changed. 

Many  of  the  illustrations  in  this  book  are  purely  diagram- 
matic and  are  intended  as  guides  and  not  completed  work  to  be 
copied  by  the  pupil ;  many  others  are  from  drawings  made  by 
the  author's  students  and  are  such  as  can  be  readily  made  by 
most  high-school  pupils. 

A  text-book  in  botany  is  a  guide,  and  it  is  neither  neces- 
sary nor  desirable  that  the  class  should  follow  it  in  all  details. 
The  teacher  should  select  such  exercises  in  this  or  other  books 
as  may  suit  the  purpose  and  should  make  such  variations  and 
additions  as  may  be  desirable.  Supplementary  reading  along 
the  lines  of  plant  geography,  and  economic  botany,  observations 
in  field,  forest  and  stream,  and  home  studies  in  the  growing  of 
plants  should  be  encouraged.  The  success  or  failure  of  the 
course  in  botany  is  more  dependent  on  the  teacher  than  on  the 
books,  laboratories  and  equipment.  A  good  teacher  is  more 
necessari/  than  hooJcs,  lahoratories  ayid  equipment.  The  acquire- 
ment of  industry,  enthusiasm,  methods  of  work,  self-reliance, 
close  ^.observation  and  accuracy  on  the  part  of  the  pupils  are 
much  more  desirable  than  much  of  the  so-called  knowledge  that 
consists  of  disconnected  or  questionable  facts. 

Mel.  T.  Cook. 
Rutgers  College, 

New  TJRtTNswicK,  N.  J. 


CONTENTS 


Preface v 

Introduction ix 

Equipment  and  Methods xiii 

PART  I.— PLANT  LIFE 

CHAPTER 

I.  Seeds  and  Seedlings 3 

II.  Roots 18 

III.  Stems  and  Buds 31 

IV.  Leaves 45 

V.  The  Flower 54 

VI.  Reproduction 74 

VII.  Fruits  and  Seeds 83 

VIII.  Anatomy  op  Stems,  Roots,  and  Leaves 93 

IX.  Chemical  Composition  of  the  Plant 105 

X.  Plant  Foods  and  Plant  Growth Ill 

XI.  The  Gymnosperms 121 

XII.  Ecological  Relations 126 

XIII.  Forestry 134 

XIV.  Plant  Diseases 139 

XV.  Plant  Breeding 147 

XVI.  Weeds 150 

XVII.  Pteridophytes 158 

XVIII.  Bryophytbs 164 

XIX.    THALLOPHYTiES 169 

XX.  Bacteria 177 

PART    II.— MOST    IMPORTANT    FAMILIES    OF    ECONOMIC 
PLANTS,  WITH  SPECIAL  EXERCISES 

XXI.  Important  Families  of  Plants 183 

Mustard — Crucifer^e 185 

Violet— VioLACE^ 189 

Mallow — Malvaceae .• 191 

Sterculia — Sterculiace^ 193 

Flax — Linace.e 193 

Rue — RuTACEiE 195 

ix 


X  CONTENTS 

Vine — Vitace^ 196 

Soap  Berry — Acerace^ 198 

Pea — Legdminose^ 199 

Rose — Rosacea 204 

Saxifrage — Saxifragace^ 211 

Gourd — Cucurbitace.e 211 

Parsley — Umbellifer.e 215 

Madder — Rubiace.e 215 

Sunflower — Composit.^ 216 

Heath — ^Vacciniace^ 217 

Convolvulus — Contolvulace.'g 218 

Nightshade — Solanace^ 219 

Goosefoot — Chenopodiace^ 221 

Buckwheat — Polygon ace^ 222 

Nettle — Urticace^ 223 

Walnut — Juglandace^ 225 

Oak — Cupulifer^ 226 

Willow — Salicace^ 227 

Banana — Zingibreace^ 227 

Lily — ^LiLiACEiE 228 

Grass — Gramine^ 228 

XXII.  Special  Exercises  with  Plant  Families 234 

Appendix — References 243 


INTRODUCTION 


^ 


6 


7- 


Botany  is  a  science  of  the  very  greatest  importance  but 
one  which  is  frequently  misunderstood  and  neglected  in  our 
educational  system.  To  many  people,  it  means  the  learning  of 
scientific  names  of  plants,  but  this  is  an  incorrect  idea.  Botany 
is  neither  the  study  of  flowers  nor  the  learning  of  scientific 
names.  Botany  is  the  study  of  plants  and  plant  life.  It  is  of 
great  importance  because  plant  life  is  absolutely  necessary  for 
the  existence  of  all  animal  life,  including  mankind.  We  are 
dependent  either  directly  or  indirectly  upon  the  plants  for  food, 
clothing,  building  materials,  fuel  and  many  other  necessaries. 
We  use  plants,  or  animals  which  have  fed  on  plants,  for  food. 
Every  article  of  food  on  the  table,  except  the  salt  and  water, 
is  derived  from  plants  or  from  animals  which  are  dependent 
on  plants  for  food.  We  use  cotton  and  linen,  and  many  other 
vegetable  fibres,  for  clothing  and  many  other  purjxtses;  and 
we  also  use  wool  and  silk  which  are  derived  from  animals  that 
have  fed  on  plants.  We  use  wood  for  building  purposes,  for 
making  furniture  and  parts  of  tools  and  implements,  and  for 
the  making  of  paper  pulp.  We  use  wood  and  coal  and  oil, 
which  are  derived  from  plants,  for  fuel.  And  finally,  we  go 
to  the  plants  for  about  90  per  cent  of  the  dl1^gs  to  relie\'e  our 
aches  and  pains  and  restore  us  to  health. 

^  When  we  once  realize  our  absolute  dependence  on  plant  life, 
we  also  begin  to  think  something  about  the  number  of  industries 
that  are  dependent  on  plants.  The  farmers,  the  horticulturists, 
the  gardeners,  the  florists  and  the  foresters  are  not  the  only 
people  who  are  dependent  on  plaaits  for  a  livelihood.  Practically 
all  manufacturing  industries  are  dependent  on  plants  in  some 
form;  for  fuel  if  for  nothing  else.  Even  the  electric  establish- 
ments must  use  fuel  to>  run  the  niachiiierv  for  t]m  u'eneration  of 


XU  INTRODUCTION 

_eLaetarrcrty.  When  we  think  of  these  things  we  wonder  why  it  is 
that  man  has  not  given  more  attention  to  this  jjrimarv  source 
of  life,  health,  wealth  and  happiness;  why  he  has  not  given 
more  attention  to  increasing  it.  The  answer  lies  in  the  fact  that 
nature  is  good  to  us ;  nature  has  supplied  man  with  the  neces- 
saries and  more,  and  man  has  been  satisfied.  But  with  the  in- 
creasing population  it  will  become  more  and  more  necessary  for 
man  to  study  plants  and  plant  life  and  to  learn  the  secrets  of 
nature  which  \nll  enable  him  to  increase  the  production  of  val- 
uable plants. 

Plants  have  influenced  the  migTation  of  man.  In  the 
account  of  his  journeys  of  discovery  and  exploration  he  has 
always  given  much  attention  to  the  character  of  the  plant^life. 
And  most  of  the  permanent  settlements  of  importance  have 
depended  on  the  character  of  the  plant  life  and  the  possibilities 
for  agriculture.  Big  factories  may  have  been  located  where 
the  water  power  was  good,  but  they  must  also  be  accessible  to 
the  raw  materials  to  be  used ;  or  they  may  have  been  located  near 
the  gTeat  beds  of  coal,  oil  or  natural  gas  and  in  that  case  they 
were  dependent  upon  the  plant  products  of  past  ages.  How- 
ever, the  great  migrations  of  the  world  have  always  been  along 
the  lines  of  great  plant  growths,  and  the  early  settlements  in 
America  and  the  rapid  progTess  of  the  American  people,  with 
which  you  are  familiar,  are  ample  proofs  of  these  statements. 

But  this  is  not  all ;  the  great  joy  of  life  is  in  life  itself.  To 
fully  enjoy  the  life  within  us  we  must  take  pleasure  in  the  life 
around  us.  The  joy  of  the  country,  of  the  forests  and  plains, 
the  mountains  and  valleys,  of  the  parks  and  gardens,  }i^not  only 
in  their  beauty  but  in  the  appreciation  of  the  value  of  the  plant 
life  which  makes  them  beautiful. 

Botany  cannot  be  studied  like  most  subjects ;  it  does  not  con- 
sist in  committing  facts.  It  cannot  be  learned  from  books,  for 
there  is  no  botany  in  books.  Books  contain  a  feiv  plans  and 
methods  for  studv ;  a  fev  records  of  observations  and  studies 


/V 


INTRODUCTION  xiii 

already  made;  a  few  facts  already  learned.  The  plans  and 
studies  may  be  changed  to-morrow ;  the  records  of  observations 
and  studies  will  be  increased ;  and  many  of  the  supposed  facts 
may  prove  to  be  errors  and  be  supplanted  by  other  statements. 

^Q,_5ve  must  not  study  books ;  we  can  use  the  books  as  guides, 
but  we  must  study  the  plants  themselves.  Louis  Agassiz  said, 
'''  Study  Nature,  not  Books" ;  and  in  studying  botany,  we  should 
stud^^  t4ieaiati«'©-<?f-  plants  and  not  the  nature  of  books.  In  this 
brief  work  we  can  give  but  very  few  of  the  best  known  and 
simplest  plans  and  methods  for  study  and  a  very  brief  state- 
ment of  facts.  Many  volumes  have  been  written  on  botanical 
subjects,  and  botany  is  now  recognized  as  well  worthy  of  the 
time  and  attention  of  the  most  learned  men  and  women  of  our 
age.  When  we  compare  the  knowledge  that  we  have  of  plant 
life  with  the  many  problems  of  plant  life  yet  unsolved  we 
realize  that  we  know  but  very  little  of  the  subject.  Plant  life 
lends  itself  so  readily  to  observation  and  study  that  the  pupils 
of  a  beginning  class  may  quickly  learn  many  things  not  recorded 
in  your  text-book. 

The  first  question  that  you  ask  when  you  see  a  strange 
plant  is,  what  is  its  name  ?  We  learn  to  know  plants  by  their 
common  names,  but  the  common  names  used  in  one  part  of  the 
country  may  be  entirely  different  from  those  used  in  another 
part,  and,  of  course,  the  common  names  must  be  different  in 
different  languages.  Therefore,  it  is  necessary  for  the  botanists 
to  use  scientific  names  (mostly  Latin)  which  will  be  the  same 
in  all  parts  of  the  world  and  in  all  civilized  languages.  But 
these  names  must  also  show  something  else,  they  must  show  the 
relationship  of  plants.  This  working  out  of  the  relationship  and 
classifications  of  plants  is  kno-\\ni  as  systematic  hofany  or  tax- 
onomy.   This  subject  will  bo  considered  again  in  Chapter  V. 

But  this  is  only  one  phase  of  botany.  We  should  know 
something  of  the  structure  of  plants,  of  the  parts  of  which  they 
are   composed.      This   study   involves   the   comparison    of   the 


XIV  INTRODUCTION 

different  parts  of  the  plant  and  the  comparison  of  the  parts  of 
ou,o  phmt  with  those  of  another  kind.  It  is  known  as  morphol- 
(xjy  and  will  be  the  basis  of  much  of  our  study. 

But  there  is  still  a  third  phase  of  botany,  the  studies  of  the 
activities  of  j^hints,  their  methods  of  securing  food,  their  growth, 
their  reproduction  and  their  behavior  in  general.  This  is 
known  as  plant  physiology  and  will  also  be  the  basis  of  much 
of  our  study.  Let  us  always  remember  that  plants  are  living- 
things  just  as  much  as  animals  are  living  things  and  should  be 
studied  as  such.  "<^.<^/''  1 

Therefore,  we  may  say  that  there  are  three  great  divisions  of  ^^ 
botany,  taxoaomYj  mokphology  and  physiology.  However,  Qi/*-'f^ 
we  have  made  many  other  divisions  of  the  subject  which  are 
more  or  less  artificial,  but  which  are  very  convenient  for  study. 
The  most  important  are:  Agricultural  botany,  horticultural 
hota^iy,  floriculture,  forestry,  plant  patJiology,  pharmaceutical 
botany,  plant  geography  and  many  other  divisions  to  please  the 
individual  workers.  But  they  must  all  depend  on  some  one, 
two  or  all  of  the  three  great  divisions.  We  will  give  some 
attention  to  them  later. 

There  is  much  to  be  gained  in  the  study  of  plants  that  is 
more  far-reaching  than  the  subject  of  botany.  After  all,  our 
education  consists  more  in  training  than  in  facts  learned.  We 
cannot,  in  the  short  time  allowed  to  the  subject,  expect  to  learn 
much  about  many  thousands  of  plants,  growing  under  the  varied 
conditions  found  in  the  different  parts  of  the  world,  but  we  can 
learn  certain  principles  of  plant  growth.  We  can  also  learn  to 
be  close  observers  of  both  the  plant  and  animal  life  around  us 
and  we  can  also  learn  to  be  accurate  in  our  observations,  in  our 
experiments  and  in  making  records.  If  we  learn  close  observa- 
tion and  accuracy  in  our  work  we  will  have  gained  a  training 
well  worth  all  the  time  devoted  to  this  subject ;  a  training  which 
will  be  helpful  in  any  future  trade,  business  or  profession  that 
we  mav  enter. 


EQUIPMENT  AND  METHODS 

The  necessary  equipment  for  a  course  in  botany  will  vary 
with  the  time  devoted  to  the  subject  and  the  available  labora- 
tory space.  If  you  do  not  have  a  laboratory,  many  interesting 
studies  can  be  made  and  experiments  conducted  in  the  ordinary 
school-room. 

The  simplest  possible  equipment  is  a  good  pocket  knife,  a 
small  hand  lens,  a  note-book  suitable  for  drawings  and  records 
and  a  reasonably  hard  lead  pencil. 

To  this  equipment  may  be  added  flower  pots,  tin  cans,  bot- 
tles, glass  jars,  glass  and  rubber  tubing,  boxes,  seeds,  bulbs, 
fruits,  vegetables,  living  plants,  sands  and  soils.  The  amount 
and  variety  of  supplies  of  this  kind  will  depend  on  the  available 
space  for  the  work.  Practically  all  of  these  supplies  can  be 
secured  from  the  local  merchants  or  collected  in  the  vicinity. 

The  laboratory  should  be  well  lighted  and  properly  heated 
both  day  and  night,  and  should  be  supplied  with  tables,  shelves, 
water  and  a  dark  room. 

The  library  sTiould  contain  as  good  a  supply  of  text-books  on 
general  botanical  and  agricultural  subjects  as  is  possible  to 
secure.  The  daily  work  should  ahvays  he  supplemented  ivith 
readings  on  hoianical  suhjeds.  The  study  of  botany  may  be 
correlated  with  many  other  subjects,  especially  chemistry, 
physics,  geology,  soils,  geography,  aginculture,  horticulture,  gar- 
dening, agi'onomy,  meteorology,  and  history. 

The  indoor  studies  should  always  be  supplemented  by  out- 
door studies.  Walks  in  the  parks  or  country  after  school  hours, 
or  on  a  Saturday,  will  prove  exceedingly  advantageous.  The 
grovring  of  plants  at  home,  the  determining  of  the  number  of 
different  kinds  of  trees  in  a  piece  of  w^oodland,  along  a  street  or 
in  a  park  are  usually  both  interesting  and  helpful. 

XV 


xvi  EQUIPMENT  AND  METHODS 

The  iiuiuber  of  dissecting  and  compound  microscopes  will 
depend  on  the  number  of  pupils  and  the  time  allotted  to  the 
subject.  Secondary  schools  have  but  very  little  use  for  micro- 
scopes and  can  get  along  very  nicely  without  them.  They  should 
not  be  nsed  except  for  the  demonstration  of  a  few  points  on  the 
structure  of  the  plants.  It  is  far  better  that  the  pupil  have  a 
good  understanding  of  a  few  fundamental  principles  of  plant 
gro\vth  than  a  poor  understanding  of  plant  structure. 

There  is  no  hard  and  fast  line  between  botany  and  agTicul- 
ture  and  horticulture,  and  in  the  agricultural  high  schools  it 
may  be  found  desirable  to  merge  these  subjects  into  a  continu- 
ous course  on  plant  studies,  but  neither  the  teacher  nor  the  pupil 
should  ever  lose  sight  of  the  fundamental  principles  of  plant 
growth.  Study  plants  and  plant  gi-owth  first  and  agriculture 
and  horticulture  will  follow  in  due  course. 

The  sciences  are  the  most  variable  subjects  taught  in  our 
schools ;  new  discoveries  cause  continuous  change  of  views  and 
methods  and  present  ne^v  lines  of  thought.  Although  bottiny  is 
in  some  respects  the  oldest  of  the  sciences  the  fact  that  its  great- 
est developing  has  been  within  the  last  quarter  of  a  century 
makes  it  the  youngest.  These  facts  explain  the  great  diversity 
of  opinion  as  to  the  importance  of  the  subject,  the  time  devoted 
to  it,  and  the  amount  and  character  of  equipment. 

The  author  fully  appreciates  that  no  teacher  can  dictate 
methods  of  teaching  botany  to  another  teacher,  but  suggestions 
may  be  given  which  are  well  worth  consideration.  The  first 
suggestion  that  the  author  makes  is  that  the  pupils  should  recog- 
nize the  importance  of  the  subject.  Botany  should  appeal  to 
the  every-day  life  of  the  students;  the  pupils  learn  to  read,  that 
they  may  read  not  the  one  exercise  at  the  set  period,  but  that 
reading  may  be  used  by  them  for  pleasure  and  business  in  every- 
day life;  they  learn  arithmetic  not  for  the  class  period  but  that 
it  may  serve  them  in  their  vocational  work ;  and  they  should 


EQUIPMENT  AND  METHODS  XVii 

study  botany  with  the  idea  that  it  is  to  bo  of  future  use,  that 
it  may  help  to  earu  a  livelihood,  that  it  may  contribute  to  the 
joy  of  living. 

Botany  should  be  taught  differently  from  most  subjects. 
History  may  be  more  or  less  complete,  truthful  records  and  de^- 
ductions ;  mathematics  may  be  exact ;  but  natural  science  implies 
doubt,  and  the  pupils  should  approach  the  experiment  with 
doubt  and  with  the  determination  to  secure  an  honest  result. 
Of  course,  the  pupil  cannot  be  expected  to  test  every  statement 
in  the  literature,  most  of  these  experiments  must  be  left  for 
another  and  more  advanced  worker ;  but  doubt  is  one  of  the  solid 
foundation  stones  of  scientific  work.  ISTo  one  will  ever  fully 
appreciate  or  enjoy  any  science  who  does  not  approach  the  sub- 
ject armed  with  an  interrogation  point. 

The  order  of  the  subjects  and  experiments  will  depend  on 
the  pleasure  and  judgment  of  the  teacher.  It  is  not  always 
necessary  to  follow  the  outline  given  in  this  or  any  other  book. 
Begin  with  any  topic  to  suit  your  own  ideas.  Most  teachers  will 
find  it  desirable  to  work  from  the  known  to  the  unknown,  but 
the  problematical  side  should  be  kept  clearly  in  view.  The 
experiments  should  be  prepared  with  the  greatest  possible  care 
and  accuracy;  and  originality  in  apparatus  and  method  should 
be  encouraged.  The  interpretations  and  conclusions  drawn  by 
the  students  should  be  carefully  guarded  by  the  teacher.  As 
much  attention  should  be  given  to  the  control  or  check  as  to  the 
experiment  itself.  The  records  should  be  full  and  complete  and 
both  drawings  and  records  should  be  accurate  and  neat. 

Mechanical  methods,  the  rock  on  which  nature  study  was 
wrecked,  should  be  avoided.  All  work  should  have  an  objective. 
Devise  or  select  exercises  from  other  books,  use  other  materials 
than  those  suggested,  or  any  and  all  other  possible  methods  to 
prevent  "  rule  of  thumb  "  work. 

One  of  the  oldest  devices  In  teaching  botany  was  the  making 


xviii  EQUIPMENT  AND  METHODS 

of  collections  under  the  belief  that  the  2)npils  would  thus  learn 
to  know  plants.  It  is  not  necessary  to  explain  the  shortcomings 
of  this  method  to  any  who  have  tried  it.  We  all  appreciate 
the  importance  of  having  pupils  know  the  common  plants,  but  a 
knowledge  of  the  laws  of  plant  growth  and  of  the  relations  of 
plant  groups  is  of  much  greater  importance  than  scientific 
names.  Collections  should  be  made  in  the  same  manner  as 
experiments,  i.e.,  with  an  objective.  Collections  illustrating 
certain  groups  of  plants  or  a.  certain  number  of  groups,  or  of  the 
jilants  of  a  locality,  or  of  the  economic  plants,  or  of  the  plants 
used  in  certain  industries  may  often  be  made  with  great  profit. 
Additional  work  for  the  bright  and  willing  students  is  to 
be  encouraged.  Pupils  with  a  love  for  the  work  will  do  much 
more  than  the  requirements  and  are  the  real  joy  of  the  teacher. 


PART  I 

PLANT  LIFE 


APPLIED 
ECONOMIC  BOTANY 

CHAPTER  I 
SEEDS  AND  SEEDLINGS 

The  seeds  of  a  plant  are  such  familiar  objects  that  most  of 
us  fail  to  appreciate  their  very  great  importance.  Of  course, 
we  know  in  a  general  way  that  a  new  plant  may  come  from  a 
seed  and  that  the  seeds  of  this  new  plant  will  produce  other 
plants.  We  also  know  that  the  seeds  of  many  plants  are  used 
as  food  by  man  and  beast.  However,  few  people  have  any  very 
clear  ideas  of  the  structural  or  chemical  characters  which  make 
the  seeds  of  some  plants  valuable  for  food  while  the  seeds  of 
others  are  useless  for  this  purpose.  N'either  do  they  have  a 
very  clear  conception  of  the  parts  of  the  seed  which  produce  the 
parts  of  the  young  plant  and  the  conditions  necessary  for  their 
development.  Let  us  examine  and  compare  a  few  seeds  and 
try  a  few  experiments  with  the  seeds  of  different  plants  to 
determine  these  points. 

Parts  of  a  Seed. — The  seed  is  a  young  plant  and  its  food 
supply.  It  is  in  a  dormant  or  resting  state  and  is  waiting  for 
the  necessary  conditions  before  growing  into  the  form  generally 
recognized  as  a  living  plant.  The  most  important  parts  of  a  seed 
are,  (a)  a  miniature  plant  known  as  the  embryo  and  which 
under  certain  conditions  will  develop  into  a  full-grown  plant ; 
(h)  an  ample  supply  of  exceptionally  nutritious  food  for  the 
nourishment  of  the  new  plant  or  seedling  until  it  becomes  self- 
supporting;  and  (c)  the  necessary  protective  covering  (Figs. 
1,  2  and  3). 

The  little  plant  within  the  seed  is  complete  in  itself.     It  pos- 

.3 

nOPERTY  LIBRARY 
N.  C  State  College 


4  SEEDS  AND  SEEDLINGS 

sesses  all  the  organs  of  a  mature  plant ;  root,  stem  and  leaf.  All 
the  other  parts  of  a  plant  with  which  we  are  familiar,  such  as 
liowers  and  fruits,  are  moditications  of  these  primary  organs. 
The  food  within  the  seed  is  especially  well  suited  for  nourishing 
the  young  plant  during  the  early  stages  of  its  development  and 
under  favorable  conditions  of  warmth  and  moisture  is  readily 
utilized  for  this  purpose.     The  highly  nutritious  character  of 


Fig.  1. — a,  diagrammatic  under-side  view  of  a  grain  of  corn  showing  the  embryo  (em)  and 
the  layers  of  food;  b,  longitudinal  section  of  corn  showing  same  parts;  c,  cross-section  of 
grain  of  corn  showing  the  same  parts. 


this  stored  food  makes  many  seeds,  such  as  corn,  wheat,  oats, 
beans  and  peas  especially  useful  as  food  for  man  and  animals. 
(Chapter  IX.)  The  outside  coverings  of  different  kinds  of 
seeds  are  ecxtremely  variable  in  character  and  have  many  modi- 
fications, some  of  which  aid  in  their  distribution.  These  points 
will  be  discussed  later.     (Chapter  VII.) 

Two  Classes  of  Seeds. — Seeds  are  extremely  variable  in 
size,  shape  and  color,  but  they  can  be  readily  grouped  into  two 
main  classes,  monocotyledons  and  dicotyledons,  dependent  on 
whether  they  possess  one  or  two  cotyledons  or  primary  leaves. 
These  cotyledons  are  easilv  recognized  in  most  large  seeds,  such 


STORAGE  OF  FOOD 


as  the  bean,  which  is  made  up  ahuost  entirely  of  two  large 
cotyledons.  These  two  classes  include  all  the  true  Howering 
plants  which  are  frequently  referred  to  as  monocots  and  dicots, 
or  mono  and  dicotyledonous  plants.  Our  common  Indian  corn 
is  a  good  example  of  the  first  and  the  common  bean  of  the  second 
of  these  groups. 

Storage  of  Food. — There  are  two  general  types  of  storage 
of  food  in  seeds.     In  some  seeds  the  entire  food  supply  is  to 


Fig   2. — Seed  of  lima  bean;  a,  b,  showing  micropyle   (mi)   and  hiluni  (h);  c,  with  seed 
coat  and  one  cotyledon  removed  showing  root  hypocotyl  (hy)  and  plumule  (pi) ;  d,  germination. 


Fig.  3. — Seed  of  castor  oil  plant;   a  and  b,  upper  and  lower  surfaces;  c,  after  removal  of  the 
seed  coat;  d,  e,  cotyledon  showing  leaf  characters. 

be  found  in  the  cotyledons,  as  in  the  case  of  the  bean  (Fig.  2), 
while  in  others  the  food  is  found  in  the  cells  which  immediately 
surround  the  little  embryo  plant,  as  in  the  corn  and  the  so-called 
castor  bean.  f"Pigs.  1  and  3.")  Tn  these  latter  cases  the  cotyle- 
dons frequently  serve  as  organs  through  wliicli  the  stored  food 


6  SEEDS  AND  SEEDLINGS 

passes  to  the  young  growing  plant.  In  some  seeds,  of  which 
corn  is  a  good  example,  the  only  apparent  function  of  the  coty- 
ledon is  for  absorption  of  the  stored  food,  but  in  the  castor  bean 
the  cotyledons  serve  first  for  absorption  and  later  as  foliage. 
In  some  seeds  the  cotyledons  serve  for  storage  only,  but  in  others 
they  serve  for  storage  and  as  the  first  leaves. 

The  corn,  bean  and  castor  bean  are  most  excellent  types  for 
study.  They  are  easily  secured,  large  and  easily  handled,  and 
possess  all  the  characters  commonly  found  in  seeds.  They  illus- 
trate all  the  preceding  points  concerning  cotyledons  and  food 
supply. 

A  grain  of  corn  is  flat,  almost  triangular  in  shape  and  has 
a  depression  or  groove  on  one  side.  Lying  beneath  this  groove 
is  the  little  embryo  plant  with  its  root  turned  towards  the  point 
of  the  grain,  and  the  stem  and  cotyledon  towards  the  large  end. 
The  embryo  plant  is  almost  surrounded  by  the  tip  or  endosperm 
starch.  The  remainder  of  the  grain  is  made  up  primarily  of 
starch,  which  is  covered  with  a  thin  layer  of  gluten  and  a  thin 
membranous,  horny  coat.  The  corn  is  not  a  simple  seed  in  the 
same  sense  that  the  bean  is  a  simple  seed.  You  will  recall  that 
the  bean  seed  is  removed  from  the  pod.  But  the  grain  of  corn 
is  not  taken  from  a  pod.  In  fact,  the  thin  membranous  horny 
coat  just  referred  to  is  the  pod  which  adheres  to  the  seed  cover- 
ing or  seed  coats.  Therefore,  the  grain  of  com,  as  we  shall  learn 
later,  is  not  a  simple  seed,  but  a  fruit.  The  grain  of  corn  con- 
sists of  the  embryo  plant,  surrounded  by  the  stored  food  and  en- 
closed in  a  thin  membranous  covering  consisting  of  the  united 
seed  coat  and  pod.  The  grains  of  wheat,  oats  and  other  grasses 
possess  similar  characters.  (Fig.  1.)  The  embryo  consists 
of  a  single  cotyledon  (or  primary  leaf),  a  short  stem  and  a 
short  root. 

The  seed  of  the  bean  is  very  different  from  the  grain  of  corn. 
The  two  large  fleshy  parts  are  the  cotyledons  and  since  there 
are  two  of  them  it  is  a  dicotyledonous  seed.     They  are  the 


CONDITIONS  FOR  SPROUTING  7 

primary  leaves  and  they  also  contain  the  food  supply.  They  are 
united  by  a  very  short  embryonic  stem,  known  as  the  hypocotyl 
{i.e.,  the  part  below  the  cotyledons).  Of  course,  this  hypocotyl 
is  very  short,  but  from  one  end  arises  the  primary  root,  which 
is  known  as  the  radicle,  while  at  the  opposite  end  we  find  the 
minute  bud  known  as  the  epicotyl  (i.e.,  the  part  above  the 
cotyledons).  These  parts  are  covered  by  the  seed  coats  which 
show  certain  markings.  The  scar,  marking  the  point  of  attach- 
ment, is  known  as  the  liilum.  On  one  side  of  this  hilum  we 
find  a  slightly  raised  ridge  known  as  the  raphe  and  on  the  other 
side  we  find  a  minute  opening  known  as  the  micro pyle,  (Fig.  2.) 

The  seed  of  the  castor  plant  is  dicotyledonous  like  the  bean, 
but  the  food  is  stored  as  an  endosperm  around  the  embryo,  as 
in  the  case  of  the  com,  instead  of  in  the  cotyledons,  as  in  the 
bean.  The  arrangement  of  the  various  parts  of  the  embryo  is 
the  same  as  in  the  bean,  but  the  cotyledons  are  very  thin  and 
show  their  leaf-like  character  very  distinctly.  The  entire  em- 
bryo is  surrounded  by  the  food  supply  which  is  enclosed  within 
the  seed  coats.  At  the  tip  of  the  seed  there  is  a  mass  of  spongy 
material,  covering  the  hilum.  It  is  called  the  caruncle  and  will 
\)e  discussed  later.  (Page  12.)  The  embryos  of  monocoty- 
ledonous  seeds  are  usually  smaller  than  those  in  dicotyledon- 
ous seeds.  The  food  supply  in  the  former  is  always  found  sur- 
rounding the  embryo,  while  in  the  latter  it  may  be  either  around 
the  embryo  or  in  the  enlarged  cotyledons.  Embryos  in  which 
the  food  is  in  the  cotyledons  are  usually  more  advanced  in  their 
development  before  ripening  than  those  in  which  the  food  sur- 
rounds the  embryo.  In  the  former  the  embryo  has  absorbed 
its  food  supply  before  ripening,  while  in  the  latter  it  must  be 
absorbed  during  germination.  (Fig.  3.) 

Conditions  for  Sprouting — When  the  seeds  of  most  plants 
are  ripe  they  can  be  stored  in  a  dry  place  and  kept  for  a  long 
time,  and  then  used  for  planting.     But  of  course,  the  seeds  of 


8  SEEDS  AND  SEEDLINGS 

the  uncultivated  or  wild  plants  are  not  stored,  tliej  remain  weeks 
or  months  exposed  to  the  weather  and  when  the  conditions  are 
favorable  they  germinate  readily  and  grow.  The  seeds  of  some 
plants  will  grow  iimnediately,  but  the  seeds  of  most  plants  will 
not  grow  until  they  have  passed  through  a  period  of  rest.  The 
seeds  of  many  plants  will  not  sprout  unless  subjected  to  the 
action  of  frost.  This  is  especially  true  of  many  nuts  and  the 
seeds  of  some  other  forest  trees.  The  seeds  of  some  water  plants 
remain  in  the  water  for  long  periods  of  time  before  sprouting. 
When  the  seeds  of  a  plant  have  undergone  their  proper  period 
of  rest  and  have  been  brought  either  by  nature  or  by  man  into 
favorable  conditions  of  ivarmth,  and  moisture  and  air  they  show 
signs  of  life  and  the  embryo  plant  resumes  its  growth ;  that  is, 
it  increases  in  size  and  is  very  soon  readily  recognized  as  a 
young  plant.  During  the  early  stages  of  its  growth,  the  young 
plant  lives  on  the  food  w4iich  is  stored  in  the  seed.  By  the  time 
this  supply  of  food  is  exhausted  the  young  plant  is  sufficiently 
well  developed  and  established  to  manufacture  its  own  food  from 
raw  materials  that  are  secured  from  the  soil  and  air.  The 
three  most  essential  factors  for  the  sprouting  of  seeds  are 
warmth,  moisture  and  oxygen  of  the  air. 

Warmth. — The  most  favorable  temperature  for  most  garden 
and  field  seeds  ranges  from  85  to  95  degi-ees,  Fahrenheit,  but 
it  is  not  the  same  for  all  plants.  Some  seeds  sprout  much  earlier 
in  the  season  than  others,  while  some  weeds  sprout  in  the  sum- 
mer or  fall  and  pass  the  winter  as  growing  plants  instead  of 
being  stored  until  spring.  The  farmer  has  long  ago  learned  the 
best  time  for  his  various  crops.  Winter  wdieat,  clover  and 
grasses  are  soa\ti  in  the  fall ;  com,  oats  and  many  other  seeds  in 
the  spring. 

We  all  know  that  seeds  cannot  sprout  without  water,  al- 
though a  very  small  amount  is  necessary  for  the  sprouting  of 
some  seeds.     The  dry  seeds  of  some  plants  may  be  kept  for 


MOISTURE  9 

loug  periods  of  time,  but  when  placed  in  moist  surroundings 
tlioy  absorb  water-  rapidly  and  in  gTcat  abundance,  swell  and 
sprout  very  quickly. 

Oxygen  from  the  air  is  also  of  very  great  importance  in  the 
sprouting  of  seeds.  Even  when  seeds  are  supplied  with  the 
proper  warmth  and  the  proper  amount  of  water  but  deprived  of 
oxygen  they  will  not  grow. 


Fig.  4. — a,  Longitudinal  section  of  corn  seed  showing  the  embryo;  b  and  c,  the  germi- 
nating seed  showing  the  emergence  of  the  root  and  plumule,  the  formation  of  rootlets  and 
root-hair. 


Moisture. — However,  it  is  possible  for  the  seeds  of  some 
plants  to  have  too  much  water,  which  will  affect  the  tempera- 
ture and  interfere  with  the  plant  securing  the  necessary  oxygen. 
In  fact,  the  little  embryo  plant  may  be  smothered  or  drowned 
in  very  much  the  same  manner  as  an  animal  may  be  killed 
when  submerged  in  water,  but  of  course  it  requires  more  time. 
Every  farmer  knows  that  land  for  certain  crops  must  be  well 
drained  and  that  too  much  rainfall  in  the  spring  interferes 
with  proper  germination,  causes  grain  to  rot  in  the  field,  and 
causes  those  plants  that  survive  to  be  yellow  and  weak. 


10 


SEEDS  AND  SEEDLINGS 


Sprouting  Process. — When  the  seed  sprouts  the  root  and 
stem  of  the  embryo  plant  elongate,  the  one  growing  downward 
and  the  other  upward ;  in  some  seeds  the  cotyledons  remain  un- 
derground as  in  the  case  of  the  corn  and  the  pea  (Figs.  4  and  6), 
while  in  other  young  plants  the  cotyledons  are  carried  above 
ground  as  in  the  case  of  the  squash  and  the  bean.  (Figs.  7  and 
8.)     It  is  very  important  that  seeds  should  not  be  planted  too 

Fig.  5.  Fig.  6. 


Fig.  5. — Bean  seedling  showing  cotyledons  and  first  leaves. 
Fig.  6. — Pea  seedling.  The  cotyledons  remain  below  the  ground. 

deep,  but  this  is  especially  important  in  the  case  of  those  seeds 
which  lift  the  cotyledons  above  the  ground.  The  raising  of  the 
cotyledons  above  the  ground  is  due  to  the  elongation  of  the  stem, 
and  deep  planting  requires  unnecessary  growth  and  tends  to  the 
production  of  a  weak  plant. 

The  cotyledons  are  the  first  leaves  of  the  young  plant  and 
when  raised  above  ground  they  perform  the  duties  of  foliage 
(Figs.  5,  7  and  8),  which  wall  be  described  later.  (Page  11). 
We  have  already  learned  that  they  may  also  serve  as  storage 


SPROUTING  PROCESS  11 

for  food  (Figs.  4—8)  for  the  young  plant;  but  they  may  also 
have  a  third  function,  that  of  absorption,  as  illustrated  by  the 
germinating  corn.  (Fig.  4.)  In  the  corn  the  single  cotyledon 
has  been  so  modified  that  it  serves  as  a  special  organ  (known  as 
the  scutellum)  through  which  the  food  passes  from  the  endo- 
sperm of  the  grain  to  the  embryo.  The  pea  (Fig.  6)  and 
numerous  other  seeds  never  raise  their  food-laden  cotyledons 
above  ground,  but  draw  the  nourishment  directly  from  them, 
or  through  them  from  the  surrounding  parts  of  the  seed.  In 
the  bean,  squash  and  related  plants,  the  cotyledons  serve  for 
storage  and  also  as  first  leaves  for  a  short  time.  The  cotyledons 
of  the  squash  (Fig.  7)  persist  for  a  much  longer  time  than  those 
of  the  bean  (Figs.  5  and  8)  and  show  their  leaf-like  character 
much  better.  The  cotyledons  of  the  castor  bean  (Fig.  3)  serve 
first,  for  the  absorption  of  the  stored  food  and,  later,  as  the 
first  leaves.  It  is  very  evident  that  in  most  plants  the  leaf 
characters  of  the  cotyledons  vary  in  proportion  as  they  serve 
for  foliage  or  for  storage.  However,  it  should  be  remembered 
that  their  leaf  characteristics  vary  somewhat  from  those  of  the 
leaves  which  are  formed  later. 

The  very  rapid  sprouting  of  seeds  is  partly  due  to  certain 
peculiar  substances  known  as  enzymes  or  ferments.  These  sub- 
stances are  usually  produced  inside  the  cells  and  serve  to  digest 
or  make  soluble  or  otherwise  modify  the  food  which  is  stored 
within  the  seeds,  thus  making  it  available  for  the  young  plant. 
Probably  the  most  important  of  these  ferments  is  known  as 
diastase,  an  enzyme  which  changes  the  starch  into  sugar  in 
very  much  the  same  manner  as  the  ptyalin  of  the  saliva  in  our 
own  mouths  changes  starch  into  sugar.  The  starch  is  only 
slightly  soluble  in  water,  but  the  sugar  is  readily  soluble  and 
therefore  becomes  an  important  factor  in  plant  growth. 

By  the  time  the  supply  of  stored  food  is  exhausted  the  young 
plant  has  a  fairly  well  developed  root,  stem  and  leaf  system 


12  SEEDS  AND  SEEDLINGS 

enabling  it  to  carry  on  an  independent  existence.  We  will 
study  the  root,  stem  and  leaf  in  the  succeeding  chaj^ters. 

The  seeds  of  some  plants  retain  their  power  to  germinate 
much  longer  than  those  of  others.  The  harvesting  of  seeds  be- 
fore they  are  fully  ripened  is  one  of  the  most  common  causes 
of  loss  of  vitality,  but  there  may  be  other  factors  which  tend 
to  injure  seeds.  These  facts  make  it  very  important  that  seeds 
should  be  tested  and  their  power  of  germination  determined 
before  planting.     (Chapter  XVI.) 

Germination  means  the  growth  or  enlargement  of  the  young 
embryo  of  the  mature  seed.  We  have  learned  that  this  occurs 
under  the  proper  conditions  of  moisture,  temperature  and  air. 
The  young  plant  may  be  considered  a  seedling  until  it  has  used 
the  supply  of  stored  food,  and  thus  becomes  an  independent 
plant,  drawing  its  food  from  water,  soil  and  air. 

Since  we  have  three  types  of  seeds  it  is  very  probable  that 
we  will  find  three  or  more  types  of  germination.  If  we  examine 
the  seed  of  the  bean  again  we  will  find  a  very  minute  opening- 
near  the  hilum.  It  is  the  micro pijle  (Fig.  2  a  and  h)  through 
which  the  water  passes  very  readily.  If  the  micropyle  is  closed 
by  wax  the  absorption  of  water  will  be  much  slower.  The 
embryo  gradually  enlarges  and  the  first  evidence  of  growth 
that  we  see  is  the  elongation  of  the  radicle,  which  breaks  through 
the  seed  coat  near  the  hilum  and  turns  downward.  The  con- 
tinued enlargement  of  the  cotyledons  and  jDlumule  forces  the 
seed  coats  off  and  the  rapid  elongation  of  that  part  of  the  stem 
below  the  cotyledons  carries  them  above  the  surface  of  the  soil. 
This  elongated  stem  is  not  straight  at  first,  but  gradually  appears 
above  the  soil  in  advance  of  the  cotyledons  as  a  loop  which 
later  becomes  erect.     (Figs.  7  and  8.) 

The  seed  of  the  castor  plant  (sometimes  improperly  called 
castor  bean)  has  a  small  mass  of  spongy  substance  (caruncle) 
(Fig.  3  a  and  h)  covering  the  hilum  through  which  the  water 


GERMINATION 


13 


is  absorbed  and  passed  on  to  tho  other  parts  of  the  seed.  The 
taking  in  of  water  causes  both  embrjo  and  surrounding  food  (en- 
dosperm) to  swell  and  the  seed  coat  to  crack  lengthwise.  The 
appearance  of  the  radicle  through  or  near  the  hilum  is  again 


Ml 


-Different  stages  in  the  germination  of  the  sq 


our  first  evidence  of  germination,  followed  bj  the  elongation 
of  the  hypocotvl  and  the  lifting  of  the  cotyledons  above  the  sur- 
face of  the  soil  very  much  as  in  the  case  of  the  bean.  How- 
ever, the  seed  coats  persist  much  longer  than  in  the  bean  and  the 


lai 


Fig.  S. — Bean   seedling   coming   through   the   soil. 

food  is  gradually  absorbed  by  the  cotyledons.  As  the  food  dis- 
appears the  cotyledons  gradually  become  green  and  leaf-like  in 
appearance  and  function.  They  usually  fall  early,  but  are 
sometimes  retained  for  a  lono-  time. 


14  SEEDS  AND  SEEDLINGS 

The  first  evidence  of  germination  in  the  corn  (Fig.  4)  is 
the  emergence  of  the  root  sheath  enclosing  the  root  which  soon 
pnshes  through  at  the  tip.  This  is  quickly  followed  by  the 
formation  of  side  roots  which  really  arise  from  the  stem.  Imme- 
diately following  the  emergence  of  the  root  sheath,  the  coni- 
cally  rolled  leaves  (plumule)  push  out  from  the  opposite  end 
of  the  groove  and  grow  upward.  The  single  cotyledon  acts  as 
an  organ  of  absorption,  the  same  as  in  the  castor  oil  seed  but 
does  not  rise  above  the  surface  of  the  soil  and  take  on  foliage 
characteristics. 

The  primary  root  elongates  rapidly  and  produces  an  abun- 
dance of  minute  root-hairs  (Pages  25  and  26),  which  serve  for 
the  absori^tion  of  wat^'r  and  nutriment  from  the  soil.  The  stem 
elongates  and  new  leaves  are  produced. 

We  have  seen  that  the  cotyledons  serve  different  functions 
in  different  seeds ;  i.e.,  for  storage,  for  absorption  and  for  fol- 
iage. A  careful  study  of  the  characters  of  the  seeds  of  a  large 
number  of  plants  and  their  germination  will  prove  both  instruc- 


EXERCISES  WITH  8EEDS  AND  SEEDLINGS 

1.  Take  a  few  dry  beans  and  a  few  that  liave  been  soaked  in  water 
for  three  or  four  hours.  Note  the  shape,  the  point  of  attacliment  (hilum) 
and  the  small  opening  or  micropyle  near  it.  Remove  the  seed  coats  and 
note  their  horny  character.  Note  the  two  large  cotyledons ;  they  are  con- 
nected by  the  short  radicle  which  gives  rise  to  the  first  root  and  the  first 
stem  or  hypocotyl.  Note  the  plumule  or  first  bud  lying  between  the  two 
cotyledons,  just  above  and  attached  to  the  radicle.  Make  drawings  or 
diagrams,  to  sliovv  all  these  points. 

2.  Castor  Bean  Seeds. — 'Examine  a  few  castor  beans  and  compare  with 
the  beans.  Note  the  thick  bodies  (caruncles)  at  point  of  attachment.  Re- 
move the  seed  coats.  Make  a  careful  examination  and  locate  the  embryo. 
Compare  the  cotyledons  with  those  of  the  bean  and  note  that  they  are  thin 
and  leaf-like.  Note  the  character  of  the  surrounding  material.  In  what 
way  is  this  seed  like  the  bean?  How  is  it  different?  Make  drawings  or 
diagrams  and  label  the  parts. 


EXERCISES  WITH  SEEDS  15 

3.  Corn  Kernels. — Take  a  few  dry  grains  of  corn  and  a  few  that  have 
been  soaked  in  water  for  a  few  liours.  Hold  each  grain  with  the  groove 
towards  you  and  the  iK>int  or  cap  downwards.  Note  that  it  is  covered 
with  a  tliin  horny  coat  which  can  be  removed.  Within  the  groove  is  the 
young  plant  or  embryo  with  the  root  pointing  downward.  Tlie  stem 
is  partly  surrounded  by  a  single  leaf  or  cotyledon  The  entire  embryo 
is  surrounded  by  starch.  The  remainder  of  the  grain  consists  primarily 
of  two  other  forms  of  starch  varying  in  amount  in  the  ditierent  varieties. 
Cut  some  of  the  grains  lengthwise  and  some  in  cross  section,  and  examine 
the  relationsJiip  of  the  various  parts.  Make  a  series  of  drawings  or 
diagrams  to  show  the  preceding  {wints. 

4.  Write  a  comparative  description  of  these  three  types  of  seeds. 

5.  Examine  a  number  of  other  seeds  and  group  them  with  some 
of  the  above  groups  or  types. 

C.  Absorption  of  Water. — Weigh  a  small  quantity  of  dry  seeds, 
place  in  water  for  a  few  hours  and  weigh  again.  What  is  the  percentage  of 
loss  or  gain  in  weight? 

7.  Fill  a  tall  bottle  or  tube  with  dry  seeds  and  add  enough  water 
to  cover  them.  Mark  the  level  of  the  water  at  the  end  of  one,  two,  three, 
four  and  five  hours  respectively.     Explain. 

8.  Fill  a  test  tube  or  a  bottle  or  a  glass  fruit  jar  with  dry  beans,  tie 
a  strong  cloth  over  the  top  and  immerse  in  water  over  night  What  is  the 
result?    Why? 

9.  Eemove  the  seed  coats  from  a  quantity  of  dry  beans  and  weigh 
without  the  coats;  weigh  out  an  equal  amount  of  dry  beans  without 
removing  the  seed  coats.  Put  the  two  lots  in  water  for  on©  hour.  Compute 
changes  in  weight.  Put  in  water  for  an  additional  hour  and  again  com- 
pute changes  in  weight    Explain. 

10.  Take  two  lots  of  dry  bean»  of  equal  weight.  Cover  the  micropyles 
of  one  lot  with  varnish  or  sliellae  and  put  both  lots  in  wet  sand  for  two 
hours.     Weigh  each  lot  and  compute)  changes  in  weight.     Explain. 

11.  Germination. — Plant  a  quantity  of  corn,  beans,  peas,  melon, 
squash,  cucumber  and  such  other  seeds  as  may  be  desirable,  in  clean  sand. 
Remove  a  few  seeds  at  intervals  of  three  or  four  days.  Make  drawings, 
label  the  parts  and  write  descriptions  and  comparisons.  (Or,  plant  the 
seeds  at  intervals  of  three  or  four  days  for  two  or  three  weeks  and  then 
study  the  seedlings  at  various  stages  of  growth  at  the  same  time. ) 

12'.  Cut  a  small  slice  off  one  side  of  several  grains  of  corn.  Ger- 
minate these  with  an  equal  number  of  uninjured  grains  between  sheets  of 
blotting  paper.     Is  tliere  any  difference  in  time  of  germination?     Why? 

1.3.  Influence  of  Moisture,  Heat  and  Light. —  (a)  Plant  two  or  three 
kinds  of  seeds  in  wet  sand  in  a  flower  pot  and  keep  in  a  warm,  well-liglited 
place. 


16  SEEDS  AND  SEEDLINGS 

(b)  Plant  as  in   (a)   but  keep  in  a  warm,  dark  closet. 

(c)  Plant  as  in   (c)   but  keep  in  <a  cool,  well-lighted  place. 

(d)  Plant  as  in  (a)  but  use  a  glass  vessel  instead  of  a  flower  pot, 
completely  cover  with  water  and  keep  in  a  warm,  well-lighted  place. 

Examinq  all  the  above  from  time  to  time  to  determine  the  moisture, 
heat  and  light  requirements.  Write  an  account  of  results  with 
explanations. 

14.  Plant  seeds  in  a  pot,  keep  well  watered  in  a  warm  place,  but 
covered  with  a  box  permitting  the  entrance  of  light  from  one  direction. 
(The  interior  of  the  box  should  be  painted  black.)  Note  the  direction  of 
growth  of  the  various  parts.     Explain. 

15.  Work  of  Cotyledons. — Plant  several  beans  in  a  pot  and  keep  in 
favorable  condition  for  germination.  As  soon  as  the  seedlings  appear  above 
the  surface  remove  one  cotyledon  from  each  of  one-third  of  the  plants,  and 
both  cotyledons  from  each  of  one-third  of  the  plants.  Take  note  on  the 
growth  of  tlie  three  sets  of  plants  for  several  days.     Explain  difference. 

16.  Water  Requirements  for  Growth.— Select  two  flower  pots  of  the 
same  size  and  weight.  Cans  with  holes  in  the  bottoms  may  be  used.  Secure 
enough  garden  soil  to  fill  them;  sift  to  remove  all  pebbles  and  mix  thor- 
oughly to  secure  uniformity  of  character.  Fill  the  two  pots  with  equal 
amounts  (by  weight)  of  soil.  Plant  six  or  more  kernels  of  corn  in  one 
and  set  both  in  a  warm,  light  place. 

17.  Set  an  ordinary  piece  of  window  glass  in  one  side  of  a  deep  box. 
Fill  the  box  with  soil  and  plant  seeds  at  various  depths  against  the  glass, 
so  that  their  growths  can  be  observed  from  the  outside.  Cover  the  glass 
with  })lack  cloth  or  paper,  so  that  it  can  be  easily  removed  for  observation. 
Supply  the  necessary  amount  of  water,  keep  in  a  warm  place  and  note  the 
germination  and  growth  from  time  to  time.  What  is  the  proper  depth  for 
planting  seeds  of  this  kind? 

18.  Partly  fill  a  cigar  box  with  wet  sand.  Cover  the  sand  with  a  cloth 
that  has  been  ruled  into  squares.  Place  a/  certain  number  of  seeds  in  each 
square.  Cover  with  a  wet  canton  flannel  cloth,  and  put  in  a  warm  place. 
Examine  after  forty-eight  hours  and  estimate  the  percentage  of  germina- 
tion. Make  a  second  estimate  after  ninety-six  hours.  (This  experiment 
should  be  tried  with  a  number  of  diflferent  kinds  of  seeds  from  various 
sources. )     How  can  seed)  testing  be  made  of  advantage  to  the  farmer? 

19.  Put  a  few  beans  and  a  little  water  in  each  of  two  lx)ttles.  Fill 
one  bottle  with  oxygen  and  the  other  with  any  other  kind  of  gas.  Close 
both  in  svich  a  manner  as  to  prevent  the  escape  of  the  gas.  Note  the 
germination. 

20.  Gas  Formed  During  Germination. — Put  a  few:  beans  and  a  lit- 
tle water  in  each  of  two  l)ottles.     Stopper  one  with  a  good  cork  and  leave 


QUESTIONS  17 

the  other  open.     After  24  hours  test  both   with  a  Ijiiniiiig  match.     What 
is  the  result?     Explain. 

21.  Repeat,  but  instead  of  testing  with  a  mutch  pour  a  little  lime  water 
into  each.    Wha^  is  the  result?    Explain. 

QUESTIONS 

1.  What  are  the  three  most  important  part^  of  the  seed? 

2.  What  are  the  parts  of  the  embryo? 

3.  Why  are  the  seeds  of  many  plantsi  valuable  as  food  for  man  and 
animals? 

4.  Make  a  list  of  seeds  used  for  food  by  man. 

5..  What    are    the    two    main    classes    of    seeds    and    what    are    their 
characters  ? 

6.  In  what  part  or  parts  of  the  seed  is  the  food  stored? 

7.  What  are  the  functions  of  the  cotyledons? 

8.  What  are  the  hypocotyl,   the  radicle,  the  epicotyl,  tlie   hiluni,   the 
raphe,  the  micropyle,  and  the  caruncle? 

9.  What  are  the  necessary  factors  for  seed  germination? 

10.  Make  a  list  of  seeds  that  are  planted  in  the  spring, 

11.  Make  another  list  of  seeds  that  are  planted  in  the  fall. 

12.  What  does  the  sprouting  seed  obtain  from  the  air? 

13.  What  is  the  eft'ect  of  too  much  water  on  field  crops? 

14.  When   a   seed    sprouts,   what   part   comes    through    the    seed   coat 
first? 

15.  When  corn  sprouts^  what  part  is  the  first  to  appear  above  ground? 

16.  When   a    bean    sprouts,    what   part   is   the    first   to   appear    above 
ground?    W'hat  is  the  second  part? 

17.  When  a  pea  sprouts,  what  part  is  first  to  appear  above  ground? 

18.  Wliat  are  the  functions  of  the  cotyledons?     (tIvc  illustrations. 

19.  To  what  can  we  attribute  the  rapid  germination  of  the  seed? 

20.  What  are  enzymes? 

21.  Are  enzymes  found  in  the  animal  body? 

22.  If  so,  name  a  few  of  them  and  give  their  functions. 

23.  What  do  you  mean  by  "  seedling  plant"? 

24.  What  is  the  function  of  the  micropyle? 

25.  What  part  of  the  seedling  bean   stem   is  the  first  to  elongate? 
2f>.  Compare  the   cotyledons  of  the  common   bean  and   the   castor  oil 

plant. 

27.  Describe  the  opening  of  the  seed  coats  of  the  bean,  castor  oil  plant 
and  other  seeds. 


CHAPTER  II 
ROOTS 

We  all  know  that  plants  have  roots,  bnt  they  are  usnally 
buried  in  the  ground  and  thus  hidden  from  sight  and  are  not 
especially  attractive.  Therefore,  most  persons  prefer  to  study 
the  more  prominent  and  pleasing  parts  of  the  plant.  How- 
ever, no  part  is  of  greater  importance  to  the  plant  as  a  whole 
than  the  root  system.  When  the  seed  sprouts,  the  root  is  the 
first  organ  of  the  embryo  to  break  through  the  seed  coats.  (Figs. 
2  d,  4,  6  and  7  a.)  It  grows  downward,  away  from  the  light, 
but  into  the  soil  which  contains  the  food  and  water.  This  ten- 
dency to  go  downward  is  called  geotropism. 

The  soil  should  contain  the  necessary  supply  of  food  and 
moisture,  and  should  be  of  such  character  that  the  roots  can 
penetrate  it  readily  if  the  plant  is  to  make  its  normal  growth. 
But  we  shall  learn  later  that  all  plants  do  not  require  the  same 
amounts  of  moisture,  nor  the  same  amounts  and  kinds  of  food. 
The  farmer  cultivates  the  soil  for  his  crop  plants  and  thus  aids 
the  plants  in  the  work  necessary  for  their  growth. 

Extent  of  Roots. — The  root  usually  grows  very  rapidly,  and 
when  the  entire  root  system  is  compared  with  the  parts  of  the 
plant  above  ground,  it  is  found  to  be  much  more  extensive  than 
we  have  ever  imagined.  When  we  pull  a  plant  from  the  soil 
a  very  large  number  of  the  roots  are  broken  off  and  left  be- 
hind. Therefore,  we  get  a  very  imperfect  idea  of  the  root 
system  and  its  ramifications  in  the  soil.  But  if  a  plant  is  grown 
in  a  pot  of  loose  soil,  and  this  soil  carefully  washed  from  the 
roots  we  begin  to  have  some  slight  idea  of  the  very  great  value 
of  this  part  of  the  growing  plant.  It  has  numerous  branches, 
18 


GATHERING  FOOD  AND  MOISTURE  19 

many  of  which  have  a  delicate  hair-like  growth.  The  total 
length  of  all  the  roots  of  some  plants  may  be  many  times  the 
total  of  the  stem  and  branches.  The  total  length  of  all  the  roots 
of  a  mature  oat  plant  are  said  to  aggregate  154  feet,  and  those 
of  a  mature  corn  plant  1320  feet.  Of  course,  no  one  root  is 
likely  to  be  more  than  a  few  feet  in  length.  However,  some 
plants  are  known  to  produce  individual  roots  of  considerable 
length.  The  alfalfa  is  said  to  produce  single  roots  as  much  as 
31  feet  in  length  and  the  mesquites  of  the  dry  western  plains 
are  said  to  produce  individual  roots  of  as  much  as  GO  feet  in 
length.  The  greater  the  root  surface,  the  greater  the  amount 
of  food  and  water  that  can  be  secured  by  the  plant.  Of  course, 
an  increase  of  the  root  system  is  usually  necessary  to  an  in- 
crease of  the  part  above  ground. 

The  roots  serve  many  purposes  in  the  life  of  the  plants,  but 
these  duties  are  somewhat  variable  for  different  plants.  The 
most  important  functions  are  as  follows :  anchorage,  gathering 
of  water  and  food,  storage  of  water  and  food,  and  in  some  cases 
for  climbing.  The  roots  serve  as  an  anchor  by  which  the  plant 
is  held  in  place.  When  we  try  to  uproot  a  plant  or  think  of  the 
terrific  wind  storms  to  which  our  trees  are  frequently  exposed, 
we  can  appreciate  the  importance  of  a  secure  anchorage.  Some 
of  the  large  trees  of  California  are  said  to  be  thousands  of 
yeaxs  old  and,  after  battling  with  the  stonns  of  ages,  are  still 
standing,  objects  of  great  admiration. 

Gathering  Food  and  Moisture. — We  know  that  the  roots 
are  organs  through  which  water  and  much  of  the  food  materials 
enter  the  plant,  but  we  have  very  little  idea  of  the  amount  of 
water  and  food  necessary  for  plant  growth.  Our  land  plants 
require  enormous  quantities  of  water  (Page  105),  which  must 
enter  through  the  roots.  Therefore,  it  is  necessary  for  the 
roots  to  spread  through  the  soil  in  such  a  manner  as  to  reach 


20  ROOTS 

both  water  and  food.  The  soil  food  is  dissolved  in  the  water, 
and  the  two  usnally  enter  the  plant  at  the  same  time. 

The  thick,  lieshj  roots  which  are  characteristic  of  some 
plants,  such  as  the  turnip,  beet  and  radish,  serve  for  the  storage 
of  food  and  water.  Roots  of  this  kind  are  used  extensively  for 
food  by  man  and  animals.  The  roots  of  some  plants,  such  as  the 
poison  ivy,  servo  for  climbing. 

Forms  and  Arrangements  of  Root  Systems. — The  roots  of 
a  plant  are  not  as  irregular  as  many  persons  suppose ;  they 
assume  forms  and  arrangements  which  are  nearly  as  definite 
as  the  parts  above  ground.  These  forms  and  arrangements  are 
just  as  characteristic  of  many  plants  as  the  stems,  leaves,  flowers 
and  fruits.  The  roots  of  some  kinds  of  plants  go  deep  into  the 
soil,  while  the  roots  of  other  kinds  spread  out,  forming  a  mat 
just  below  the  surface. 

However,  the  arrangement  of  the  roots  of  plants  of  the  same 
kinds  will  vary  somewhat,  with  the  character  of  the  soil.  The 
most  important  soil  characters  which  influence  the  arrange- 
ment of  roots  are  texture,  depth,  fertility  and  amount  of  mois- 
ture content.  In  general,  it  may  be  said  that  in  shallow  soil 
the  roots  will  spread  near  the  surface  of  the  ground,  while  in 
deep  soil  they  will  tend  to  lie  deeper;  in  rich,  moist  soil  they 
will  be  short  and  branching,  while  in  poor,  dry  soil  they  will  be 
long  and  with  few  branches.  However,  some  plants  by  nature 
tend  to  spread  their  roots  near  the  surface,  while  others,  like 
alfalfa,  tend  to  go  deep  into  the  earth  and  are,  therefore,  espe- 
cially well  suited  for  certain  soil  conditions.  Some  crops  require 
much  deeper  and  richer  soil  and  much  more  thorough  cultiva- 
tion than  others.  The  potato  and  other  plants  with  large,  fleshy, 
underground  structures  require  loose,  deep,  rich  soil  to  thrive 
and  give  the  best  results.  A  knowledge  of  this  relationship 
between  root  systems  of  plants  and  soil  conditions  is  of  very 
great  value  in  selecting  crops  for  difl"erent  localities. 


FORMS  AND  ARRANGEMENTS  OF  ROOT  SYSTEMS 


21 


The  roots  of  some  plants  are  fibrous  (Figs.  9,  10  and  13), 
and  in  large  plants  very  woody  and  hard,  while  the  roots  of 
other  plants  are  thick  and  fleshy.  (Figs.  11  and  12.)  The 
fibrous  roots  branch  irregularly  and  serve  for  anchorage  and 
also  for  the  entrance  of  water  and  dissolved  food  materials. 


Fig.  9. — A  grass  plant  showing  the  fibrous 
root  system. 


Fig.  10. — A  bean  seedling  showing  the  bac- 
terial nodules  on  the  roots. 


The  fleshy  roots,  in  addition  to  this  work,  also  serve  as  places 
for  storage  of  large  quantities  of  foods.  Man  and  animals  take 
advantage  of  these  stored  products  and  use  the  roots  of  many 
plants  for  food.  However,  this  food  is  stored  in  the  roots  for 
the  future  use  of  the  plants  themselves  and  is  usually  an  import- 
ant factor  in  their  production  of  flowers  and  seeds.  (Page  52.) 
Some  plants  use  this  stored  food  the  same  season  that  it  is 
accumulated,  while  others  hold  it  in  reserve  for  one  or  more 


22 


ROOTS 


years.  The  radish  is  a  plant  in  which  the  food  is  used  for  seed 
production  the  same  season  that  it  is  stored.  The  turnip  develops 
the  fleshy  root  one  year  and  uses  it  for  seed  production  the 
second  year. 

Food  for  Man. — The  supply  of  stored  food  in  the  roots  of 
many  plants  makes  them  valuable  for  food  of  man  and  other 


Fig.  11. — Carrot  showing  fleshy  root.      Fig.  12. 


-Sweet    potato   showing   cluster  of  fleshy 
roots. 


animals  if  used  before  they  start  to  form  the  shoot  for  flower 
and  seed  production.  But  if  we  wait  until  this  shoot  is  well 
advanced,  we  find  the  root  becoming  dry  and  pithy,  owing  to 
the  loss  of  moisture  and  food  which  has  been  passed  on  into  this 
new  growth.  In  some  plants,  this  storage  for  future  use  is 
performed  by  the  stems  or  leaves.  (Page  51.)  The  sweet 
potato  (Fig.  12)  is  a  plant  which  seldom  produces  seeds  in  our 
northern  latitude,  but  uses  the  accumulated  food  of  the  large 


AERIAL  ROOTS  23 

fleshy  roots  for  the  inimediate  production  of  new  plants  or 
slips.  Sometimes,  new  plants  are  also  produced  directly  from 
fibrous  roots,  as  in  the  case  of  the  poplar,  plum,  etc.,  but  as 
a  rule  new  plants  are  not  produced  from  the  roots. 

Length  of  Life.-    Plants  which  live  but  one  year,  as  in  the 
case  of  the  radish  are  known  as  annuals;  those  that  live  for  tw^o 


Fig.  13. — Corn    plants   sliowing    the    aerial   roots. 

years,  as  in  the  case  of  the  turnip,  are  known  as  biennials;  while 
those  that  normally  live  for  several  years,  as  in  the  case  of 
trees,  are  known  as  perennials. 

Aerial  Roots. — Eoots  are  frequently  borne  on  parts  of  the 
stem  above  the  ground,  and  are  known  as  aerial  roots.  (Fig. 
13.)  These  roots  tend  to  reach  the  soil  and  serve  as  prop  roots 
and  help  to  support  the  plant  against  wind  storms.  They  are 
well  developed  on  the  lower  part  of  the  corn,  and  are  especially 
prominent  on  those  plants  which  have  not  been  tilled  properly. 


24 


ROOTS 


The  Banyan  tree  of  the  tropical  East  Indies  produces  roots 
from  its  branches  which  tend  to  reach  the  soil  and  finally  assume 
the  character  of  tree  trunks.  Some  plants,  kno%vn.  as  epiphytes, 
especially  abimdant  in  warm,  moist  climates,  often  produce 
aerial  roots  which  never  reach  the  soil  but  spread  out  into 
the  moist  air  and  serve  for  the  absorption  of  water.  The 
orchids  of  tropical  countries,  and  the  so-called  Florida  moss  of 
our  own  Southern   States  are  striking  examples  of  epiphytic 


Fig.  14. — Cross-section  of  stem  showing  dodder  attached  by  haustoria  or  parasitic  root. 

plants.  The  orchids  in  the  colder  climates  are  rooted  in  the 
soil. 

The  aerial  roots  may  also  serve  for  climbing  on  trees,  fences 
or  buildings,  stone  walls  and  other  firm  objects.  Climbing 
plants  are  frequently  injurious  to  trees,  not  only  because  their 
roots  penetrate  the  minute  crevices,  but  also  because  they  retain 
the  moisture  and  make  favorable  co-nditions  for  organisms  which 
cause  decay.  They  are  also  injurious  to  wooden  structures  on 
which  they  are  allowed  to  grow,  in  that  they  retain  moisture 
and  cause  decay. 

Parasitic  Roots. — Some  plants  feed  upon  other  plants  by 
means  of  roots  which  penetrate  them.  They  are  called  parasites, 
and  their  roots  parasitic  roots  or  haustoria.  The  mistletoe  of 
the  South  and  the  common  dodder  (Fig.  14)  which  is  much 


fHOfERTT  UBKARY 
Ji.  C.  State  Colkgi 


STRUCTURES 


25 


more  widely  distributed  throughout  the  country  are  good  illustra- 
tions of  this  type  of  roots. 

Aquatic  Roots. — Some  floating  plants  produce  roots  which 
never  penetrate  the  soil.  They  are  known 
as  aquatic  roots  and  absorb  water  and  the 
yarious  food  substances  in  solution  which 
are  necessary  for  plant  growth.  The  very 
small  but  widely  distributed  duck  weeds 
and  the  much  larger  water  hyacinth  of  the 
South  are  excellent  examples  of  floating 
plants.  However,  many  aquatic  plants, 
such  as  the  pond  lily,  cat-tails,  etc.,  have 
roots  which  penetrate  the  mud,  while  the 
plant  either  floats  or  stands  upright. 

Structures. — Roots  are  made  up  of 
three  parts,  a  central  cylinder  composed  pri- 
marily of  woody  tissue  and  surrounded  by 
a  sheath  or  cellular  cortex,  and  covered 
with  a  very  thin  epidermis  or  skin-like 
coating.  (Fig.  15.)  They  grow  in  length 
much  more  rapidly  than  in  thickness  and 
the  very  delicate  tip  is  protected  by  a  mass 
of  cells  known  as  the  root  cap.  All  parts 
of  the  root  do  not  elongate  with  equal  ra- 
pidity. There  is  a  zone  just  back  of  the 
tip  in  which  the  growth  is  most  rapid.' 
The  tips  of  roots  are  soft  and  delicate  and 
easily  broken,  yet  they  must  exert  an  enor- 
mous force  which  we  cannot  appre- 
ciate. The  surface  of  the  young  roots,  just  back  of  the  tip,  is 
covered  with  numerous  very  delicate  root-hairs  or  trichomes. 
(Figs.  4,  16  and  19.)  These  root-hairs  are  very  numerous  and 
should  be  studied  on  very  young  plants  that  have  been  grown  in 


Fig.  15. — Diagramm- 
atic longitudinal  sec- 
tion of  a  root  tip;  a, 
central  cylinder;  c, 
cortex;  e,  epidermis; 
r.  c,    root    cap. 


26  ROOTS 

a  germiuator,  and  also  on  plants  that  have  been  grown  in  loose 
soils.  They  grow  between  the  very  fine  particles  of  soil.  If 
the  plant  is  pulled  from  hard  soil  they  are  torn  olf,  but  if 
pulled  from  loose,  wet  soil,  they  are  retained  and  the  soil  clings 
to  them.  In  order  to  understand  them  it  will  be  necessary  to 
study  them  with  a  microscope. 


Fig.  16. — .Seedling  showing        Fiu.  17. — Cross-section  of  rootlet  showing  root-hairs, 
soil  held  by  root-hairs. 

Work  of  Root-Hairs. — Each  root-hair  is  a  thin-walled  cell 
containing  living  protoplasm  and  cell  sap.  This  living  proto- 
plasm has  the  power  of  absorbing  water  by  osmosis,  causing  the 
cells  to  become  very  much  expanded  or  turgid.  The  excess  of 
certain  substances  in  the  soil  may  cause  an  exosmosis  or  with- 
drawal of  water  from  the  roots  and  thus  injure  or  even  kill  the 
plant.     This  explains  one  reason  why  certain  soils  may  be 


AIDED  BY  OTHER  ORGANISMS 


27 


unsuited  for  certain  plants  and  also  how  the  farmer  may  injure 
his  crops  by  using  too  much  of  certain  fertilizers  or  by  the  im- 
proper mixtures  of  the  fertilizers  with  the  soil.  The  root-hairs 
persist  for  a  very  short  time  and  then  perish,  but  new  ones  are 
produced  near  the  growing  tips.  The  number  of  root-hairs 
varies  with  the  amount  of  water  in  the  soil.  They  are  more 
numerous  in  dry  than  in  wet  soils.     (Figs.  17,  18  and  19.) 


Fig.  18. — Showing  attachment  of  root- 
hair  to  epidermis. 


FlQ.  19. — Showing  relation  of  root-hair  to 
soil  particle. 


Aided  by  Other  Organisms. — Plants  are  frequently  facil- 
itated in  securing  their  food  by  other  organisms.  Dead  plants, 
dead  animals  and  manures  must  undergo  a  decay  before  they  are 
sources  of  available  food  for  most  plants.  This  decay  is  caused 
by  bacteria  and  fungi.  (Page  172.)  Certain  bacteria  also  aid 
the  plant  by  taking  the  nitrogen  from  the  air  and  fixing  it 
in  such  a  manner  as  to  make  it  available  for  plant  food. 
(Page  117.) 


28  ROOTS 

Roots  of  Plants  Require  More  or  Less  Air. — The  securing 
of  this  air  is  facilitated  in  many  of  our  cultivated  plants  by 
drainage  and  by  cultivation  of  the  soil,  thereby  keeping  it  loose 
so  that  the  air  penetrates  it  readily.  But  plants  growing  in  a 
state  of  nature  have  various  parts  and  organs  through  which  the 
necessary  air  is  secured.  Many  aquatic  plants,  such  as  pond 
lilies  and  cat-tails,  have  air  passages  by  which  the  air  passes  from 
the  parts  exposed  to  the  air  to  the  submerged  parts.  The  swamp 
cypress  has  peculiar  upward  root  growths  known  as  "  knees," 
which  project  above  the  surface  of  the  water  and  serve  for  the 
absorption  of  oxygen.  Many  forest  trees  have  root  growths 
extending  above  the  surface  of  the  soil  which  serve  for  the 
same  purpose.  The  filling  in  around  trees  which  is  frequently 
necessary  in  making  grades  is  injurious  because  it  prevents  the 
air  from  reaching  the  roots. 

EXERCISES   WITH   ROOTS 

1.  Direction  of  Growth  of  Roots. — Sprout  a  nvimber  of  seeds  and 
suspend  in  a  moist  chamber  on  lon^-  ])ins  or  by  means  of  threads  so  that 
the  root  tips  will  point  in  different  directions.  Examine  from  day  to  day 
and  note  the  direction  of  growth.  Small  moist  chaml>ers  can  be  made  by 
putting  a  small  amount  of  water  in  a  wide  bottle  or!  glass  jar;  run  a  hat 
pin  through  tlie  cork  for  supporting  seeds. 

2.  Direction  of  Growth  in  Soil. — Sprout  a  number  of  seeds  and  plant 
in  wet  sand  in  such  a  manner  that  the  root  tips  point  in  different  direc- 
tions. Examine  one  a  few  days  later  and  note  the  direction  of  growth 
of  roots  and  stems. 

3.  Growth  Against  Resistance. — Partly  fill  a  small  cup  with  mer- 
cury. Pour  a  little  water  on  the  surface.  Fasten  a  germinated  seed  in  such 
a  manner  that  the  root  tip  rests  on  the  mercury.  Inclose  in  a  moist  cham- 
ber for  24  hours.  Has  the  root  ti])  penetrated  the  mercury?  Does  this 
require  force? 

4.  Geotropism  or  Direction  of  Root  Growth. — Sprout  a  number  of 
beans  in  sphagnum  moss  or  other  loose  material  that  will  insure  the  forma- 
tion of  straiglit  roots.  Mark  the  roots  into  short,  equal  sections,  using 
India  ink.  pin  them  to  corks  and  place  in   large  moist  chambers  *   in  such 

*  Moist  chambers  can  be  made  by  lining  large  Ijattery  or  other  glass 
jars  with  wet  filter  paper  and  covering  so  as  to  prevent  excessive 
evaporation. 


EXERCISES  WITH  ROOTS  29 

a  manner  that  tlicy  will  point  in  various  directions.  Examine  at  tlu- 
end  of  24  hours  and  again  at  the  end  of  48  houra  Note  the  direction  of 
growth,  the  point  at  which  curving  begins  and  where  the  curvature  is 
greatest  as  indicated  by  the  marks  and  the  point  at  which  the  greatest 
growth  occurs. 

5.  Examine  the  root  system  of  a  growing  bean,  castqr  bean,  or  sun- 
Hower.  Note  the  tap  root,  the  mode  of  branching,  the  location  of  oldest 
and  youngest  branches,  size  and  shape  of  tap  root  and  branches.  Make 
drawings  or  diagrams. 

6.  Examine  the  root  system  of  growing  corn,  wheat  or  oats.  Com- 
pare the  root  system  with  tliat  in  Ex.  5.    Make  drawings  or  diagrams. 

7.  Examine  the  root  system  of  a  growing  beet,  turnip  or  radish. 
Note  the  tap  root  and  its  branches  Compare  with  that  in  Ex.  5.  Make 
drawings  or  diagrams. 

8.  Examine  the  root  system  of  tlie  dahlia  or  sweet  potato.  Compare 
with  that  in  Ex.  7.    Make  drawings  or  diagrams. 

9.  Examine  the  root  system  of  English  ivy  or  some  other  plant  or 
plants  in  which  the  roots  serve  for  climbing.  Note  their  location,  branch- 
ings and  general  character.     Make  drawings  or  diagrams. 

10.  Region  for  Root-hairs. — Sprout  a  niunber  of  grains  of  corn, 
okra,  radisli  seed,  clover  seed,  or  white  mustard,  between  wet  blotting 
paper  until  the  roots  are  abouti  one  and  one-half  inches  in  length.  Note 
the  region  on  which  the  root-hairs  occur.  Examine  the  root-hairs  under 
a  compound  microscope,  or  strong  hand  lens. 

11.  Soil  Held  by  Root-hairs. — Plant  seeds  in  fine,  sandy  soil.  After 
two  weeks  wet  the  soil  thoroughly  and  very  gently  remove  the  plants. 
Note  the  manner  in  which  the  soil  is  held  by  the  root  hairs. 

12.  Roots  from  Willow  Twigs. — Ctit  a  niunber  of  willow  twigs  about 
twelve  inches  in  length  and  put  in  a  jar  of  water  so  that  about  half  the 
length  will  be  covered.  Put  part  of  them'  upside-down.  Use  an  earthen 
jar  or  a  glass  jar  covered  with  black  paper  so  as  to  exclude  the  light. 
Examine  from  time  to  time  and  note  the  formation  of  roots.  Where  are 
they  located  and  what  is  the  direction  of  growth? 

13.  Osmosis  with  a  Thistle  Tube. — Make  an  artificial  root-hair 
by  covering  the  large  end  of  a  thistle  tube  with  an  animal  or  plant  mem- 
brane, piece  of  intestine  (sausage  covering)  or  bladder,  fill  the  bulb  with 
a  thick  syrup  (mola.^ses)  and  invert  in  a  jar  of  water  so  that  the  two 
fluids  stand  at  the  same  level.  Examine  after  a  few*  hours^  and  note  the 
rise  of  the  fluid  in  the  tube.  This  passing  of  a  fluid  of  less  density  through 
an  animal  membrane  into  a  fluid  of  greater  density  is  called  osmosis. 
(Pages  112  and  11.3.) 

14.  Osmosis  with  an  Egg. — Remove  the  shell  without  breaking  the 
skin  from  the  large  end  of  an  egg  over  an  area  about  the  size  of  a  dime. 
In  the  same  manner  remove  a  small  bit  of  shell  from  the  small  end  over 


30  ROOTS 

an  area  about  one-eighth  of  an  inch  in  diameter.  Run  a  glass  tube  through 
a  small  section  of  a  wax  candle  and  directly  over  the  small  openin};.  Now 
push  the  wire  down  the  tube  and  puncture  the  membrane  at  the  small  end 
of  the  egg.  Fill  a  wide-mouthed  bottle  level  full  of  water  and  set  the  egg 
in  the  top.     (Fig.  80.)     Note  and  explain  the  rise  of  water  in  the  tube. 

15.  Osmosis  with  a  Fleshy  Root- — Cut  a  slice  from  the  upper  part 
of  a  carrot  or  other  fleshy  root;  hollow  out  the  centre  of  the  root  and 
fill  with  sugar.  Let  stand  for  twenty-four  hours.  What  has  occurred? 
Explain. 

IG.  Cut  thin  strips,  about  one-eighth  inch  thick,  of  a  fleshy  root  and 
place  in  salt  water  for  a  few  hours.  Examine  and  then  place  in  distilled 
water  for  a  few  hours.     Examine  and  explain. 

QUESTIONS 

1.  VVliere  do  we  find  the  root  system  of  the  plant? 

2.  What  do  you  understand  by  geotropism  ? 

3.  What  are  the  characters  of  the  soil  that  make  it  suitable  for  plant 
growth  ? 

4.  What  can  you  say  about  the  different  types  of  root  systems  of 
plants  ? 

5.  What  are  the  functions  of  the  roots? 

6.  Is  there  any  difference  in  the  arrangement  of  the  root  systems  of 
plants  ?    Explain. 

7.  Upon  what  is  the  variation  of  the  root  system  dependent? 

8.  What  is  the  difference  between  the  root  system  of  the  radish  and 
that  of  the  turnip?     What  functions  do  they  serve? 

9.  Give  a  list  of  plants  whose  roots  are  used  for  food  by  man  and 
livestock. 

10.  Define  and  give  examples  of  annuals,  biennials,  and  perennials^ 

11.  What  is  the  difference  between  aerial  and  epiphytic  roots. 

12.  Name  some  plants  with  parasitic  roots. 

13.  Name  some  plants  with  aquatic  roots. 

14.  Name  and  locate  the  three  parts  of  a  root. 

15.  Explain  osmosis. 

16.  Why  are  some  fertilizers  injurious  to  plants? 

17.  How  does  air  reach  the  roots  of  plants?  How  can  the  farmer 
aid  plants  to  secure  air? 

18.  What  is  the  general  direction  of  root  growth?     Of  stem  growth? 


CHAPTER  III 


STEMS  AND   BUDS 


The  stem  is  that  part  of  the  plant  which  connects  the  root 
with  the  leaves.  The  most  common  types  of  stems  of  seed- 
bearing  plants  are  above  ground  and  serve  to  support  the  foliage 
and  flowers.  They  usually  show  more  or  less  well-defined  divi- 
sions into  nodes  (joints),  and  internodes  as  indicated  by 
branches,  leaves  and  leaf  scars,  buds  and  bud  scars.  (Figs.  20 
and  21.)  They  produce  branches  at  the  nodes  more  or  less 
regularly.  At  the  points  where  the  new  season's  growth  begins 
we  find  a  number  of  scars  very  close  together.  (Fig.  20.)  By 
examining  the  scars  we  can  usually  determine  the  amount  of 
growth  of  the  twigs  for  several  years  past. 

There  are  two  well-defined  types  of  stems,  the  exogenous 
(Fig.  22  a),  or  the  outside  growing,  and  the  endogenous  (Fig. 
23  a)  or  inside  growing.  The  former  is  much  more  abundant 
than  the  latter,  and  the  two  can  be  readily  distinguished  by  cut- 
ting them  in  cross  sections.  In  both  cases  the  stems  are  com- 
posed of  hard,  woody  bundles  surrounded  by  a  softer  substance 
which  is  covered  by  the  bark  or  protective  covering.  The  ar- 
rangement of  these  bundles  is  quite  difl^erent  in  the  two  classes. 
In  the  exogenous  stems  (Fig.  22)  the  bundles  are  almost  always 
arranged  in  a  circle  and  the  strength  of  the  stem  depends,  in 
a  large  measure,  on  their  compactness.  Such  stems  will  in- 
crease in  diameter  as  long  as  the  plant  is  alive  and  gi'owing. 
This  increase  in  diameter  is  due  to  the  formation  of  a  layer 
of  wood  just  outside  the  last  year's  growth  of  wood.  This  very 
thin  layer  of  cells  in  which  the  new  growth  is  occurring  is 
known  as  the  cambium.    These  annual  layers  are  so  distinct  that 

31 


32 


STEMS  AND  BUDS 


they  can  be  readily  seen  on  the  cut  ends  of  tree  trunks,  with  the 
naked  eye,  and  are  known  as  annual  rings.  (Fig.  24.)  All  the 
dicotyledonous  and  coniferous  jjlants  have  stems  of  this  type. 
If  you  cut  a  cross-section  of  a  soft,  rapidly  growing  stem  (be- 
gonia or  geranium),  you  can  see  these  bun- 
dles more  or  less  well  defined.  If  you  cut 
a  cross-section  of  a  woody  stem,  you  will 
readily  recognize  these  bundles  which  are  sep- 
arated by  radiating  lines. 

We  find  two  types  of  endogenous  stems. 
One  which  consists  of  a  mass  of  soft,  pithy 
tissue  surrounded  by  a  hard  rind  and  con- 
taining scattered,  woody  strings  known  as 
fibro-vascular  bundles  (Fig.  23),  and  an- 
other which  is  of  the  same  general  character, 
but  is  hollow,  and  therefore  the  fibro-vascular 
bundles  are  forced  into  the  form  of  a  cyl- 
inder. All  of  the  grass  stems  are  endogen- 
ous; the  corn  which  is  a  coarse  grass,  is  a 
good  example  of  the  first  type  and  the  various 
grains  and  most  common  grasses  are  exam- 
ples of  the  second  type.  These  fibro-vascu- 
lar bundles  or  woody  strings  can  be  readily 
recognized  in  the  corn  stalk. 

Stems  in  which  the  fibrous  bundles  are 
small  as  compared  witH  the  surrounding  ma- 
terials are   soft   and   juicy,   and  are  called 
herbaceous^  while  those  in  which  the  bundles 
constitute  the  gi-eater  part  of  the  substance 
are  called  ivondy.    Most  of  the  strictly  woody 
plants  have  exogenous  stems  and  show  rings.     (Chapter  VIII.) 
Stems  Above  Ground. — The  aerial,  or  above-ground,  stems; 
may  be  very  short  as  in  the  case  of  the  turnip  or  radish,  in  which 


FiQ.  20.— a,  maple 
twig  showing  buds,  leaf 
scar  and  annual  growth ; 
b,  horse  chestnut  twig 
showing  same. 


STEMS  ABOVE  GROUND 


33 


it  supports  a  mass  of  leaves  very  close  to  the  root  and  is  knowu 
as  a  crown  or  acaulescent  stem,  or  it  may  be  more  or  less  elong- 
ated, as  in  the  case  of  many  herbaceous  plants  and  trees.  The 
elongated  stems  may  ba  erect,  as  in  the  case  of  trees,  but 
extremely  variable  in  size  and  form.     Two  well-defined  types  of 


Z:£:::^bi.'''>^,.,.^^ri>.^'<^ 


Fig.  21. — Twig   showing   alternate   buds. 


"^^^^^ 


the  stems  are  the  excurrent  (Fig.  25),  in  which  we  find  a  tree 
with  a  central  axis  or  trunk  giving  off  numerous  small  branches, 
like  the  pine,  and  the  deliquescent  (Fig.  26),  in  which  the  main 
trunk  sub-divides  by  branching  and  loses  its  identity  as  in  the 
oak  and  elm.     Stems  belonging  to  either  of  these  types  vary 


Fig.  22. — a,  cross-section  of  dicotyledonous         Fig.   23. — a,     cross-section    of     monocoty- 
steni ;  b,  fibrovascular  bundle  from  same,    ledonous  stem ;     b,     cross-section     of     fibro- 

vascular  bundle  of  same. 


greatly  in  the  method  of  arrangement  of  the  branches.  Persons 
who  have  given  some  attention  to  this  subject  can  recognize 
many  trees  by  their  style  of  branching. 

However,  many  elongated  aerial  stems  cannot  stand  erect, 
but  are  decumheiit,  or  leaning,  as  in  the  case  of  many  berry 
plants ;  or  prostrate,  as  in  the  case  of  those  plants  which  trail 
3 


34 


STEMS  AND  BUDS 


-YneA.  fo-^ 
-arv-rvuVcvY 


Fig.    24. — Diagrammatic     cross-eeotion     of   a    trep  stem   showing   the   medullary   ray   and 
annular    ring. 


Fig.  25.^Trees  showing  the  excurrent  type  of  stems. 


along  the  ground  (ground  ivy)  ;  or  climbers,  as  in  the  case  of 
many  vines  which  cling  to  other  plants,  walls  or  buildings  for 
support.  Climbing  may  be  accomplished  by  twining  or  by 
means   of  specially  modified   branches   or   stems    (tendrils   of 


UNDERGROUND  STEMS 


35 


Fk;.  2(;.-Treo  showiiiK 


It  type  of  stem. 


grape),    or   by   rootlets    (poison   ivy),    or   by   modified   leaves 
(clematis). 

Underground  Stems. — Tlie  stems  of  many  plants  are  under- 
gronnd  and  are  freqnently  mistaken  for  roots.     However,  they 


36 


STEMS  AND  BUDS 


can  be  readily  recognized  by  the  fact  that,  like  all  stems,  they  are 
divided  into  more  or  less  regular  nodes  and  internodes,  and  the 
branching  is  ahvayni  from  these  nodes  and  is,  therefore,  regular, 
while   the    roots    are   without    nodes    and   branch    irregularly. 


Fig.  28. — a,  tulip  bulb;  b,  same  cut  longitudinally  to  show  short  basal  stem  and  fleshy 
leaf  overlapping  the  single  terminal  bud. 

Numerous  roots  are  frequently  formed  at  the  nodes  of  these 
underground  stems. 

Underground  stems  may  be  divided  into  two  general  types, 
the  elongated  and  the  short.  The  elongated  stems,  which  are  so 
well  illustrated  by  the  Solomon's  seal  and  May-apple  (Fig.  27), 


UNDERGROUND  STEMS 


37 


bear  roots  at  regular  intervals  and  show  well-defined  leaf  scars 
at  the  nodes.  Some  grasses,  such  as  the  witch  grass,  have 
similar  underground  stems  bearing  buds  at  the  nodes.  When 
such  grass  stems  are  torn  to  pieces  by  the  farm  implements  each 


^J 


\^ 


<'io.  29. — Potato  showing  the  tulier  type  of  ste 


Fig.  30. — Stem  or  trunk  of  the 
birch  showing  the  pecuHar  markings 
of  the  bark. 


bud  is  capable  of  growing  into  a  new  plant.  Such  stems  are 
called  root  stocls  or  rhizomes.  Shortened  stems  have  very  short 
internodes  and  are  generally  designated  as  bulbs  (Pig.  28)  and 
tubers  (Fig.  29).  The  bulbs  are  very  short  stems  covered  with 
scales  which  are  reallv  modified  leaves.     These  scales  may  be 


38  STEMS  AND  BUDS 

very  prominent^  as  in  the  easo  of  the  liyacintli  or  onion,  or  they 
may  be  small  and  on  a  very  short,  thick,  fleshy  stem,  as  in  the 
case  of  the  Indian  turnip.     This  last  type  is  known  as  a  conn. 

Bulbs  or  bulblets  are  sometimes  borne  on  the  stem  above 
ground;  they  are  nothing  more  nor  less  than  modified  buds. 

Sometimes  the  underground  stems  become  very  thick  and 
fleshy  and  are  known  as  tubers.  The  common  white  or  Irish 
potato  is  an  excellent  example  of  the  tuber.  The  so-called 
"  eyes  "  are  buds  and  indicate  the  nodes  of  the  stem.  True 
tubers,  such  as  the  Irish  potato,  are  fleshy  stems  and  are  entirely 
different  from  the  fleshy  roots  of  such  plants  as  the  s\veet  potato 
and  the  dahlia. 

Two  Chief  Uses  of  Stems. — As  previously  stated,  stems  con- 
nect the  roots  with  the  leaves  and  support  the  latter  in  the  air 
and  light,  but  some  plants,  such  as  the  cactus,  have  leaves  that 
are  poorly  developed  and  of  little  importance.  The  stems  of 
these  so-called  "  leafless  "  plants  are  green  and  serve  the  same 
function  as  leaves.  (Page  47.)  The  stems  of  many  other  plants 
are  also  green  and  perform  the  duties  of  lea^'es  for  a  part  or  for 
the  entire  life  of  the  plants.  The  young  twigs  are  usually  green 
and  have  stomata  (Chapter  IV),  the  same  as  leaves.  How- 
ever, these  stomata  soon  lose  their  original  character,  and  de- 
velop into  lenticles.  (Chapter  VIII. )  The  lenticles  are  the 
little  specks  which  are  so  readily  recognized  on  the  smaller  twigs. 
(Figs.  20,  21  and  30.)     They  will  be  referred  to  again. 

Stems  also  serve  for  the  passage  of  the  water  and  food  sub- 
stances from  one  part  of  the  plant  to  another.  (Chapter  VIII.) 
These  are  the  primary  functions  of  stems,  but  they  also  serve 
many  other  purposes.  In  the  cacti  and  other  plants  living  in 
very  dry  regions  they  serve  for  the  accumulation  of  considerable 
quantities  of  water.  Floating  plants  frequently  have  large 
chambers  filled  with  air  which  increases  their  buoyancy.  Many 
stems,  such  as  tubers,  serve  for  the  accumulation  of  food  sub- 


THE  ART  OF  BUDDING  AND  GRAFTING  39 

stances  for  future  use.  Mau  has  taken  advantage  of  this  fact 
and  uses  potatoes,  onions  and  many  other  fleshy  stems  for  food. 

But  one  of  the  most  important  of  the  secondary  functions 
of  the  stem  is  reproduction  This  is  accomplished  by  under- 
ground stems,  by  the  branching  and  the  breaking-up  of  the 
root  stocks,  and  by  the  budding  or  formation  of  bulblets  in  the 
bulb  types.  Many  plants,  lilies  and  hyacinths,  have  practically 
lost  their  pov^^er  to  produce  seeds  and  depend  entirely  upon  this 
method  of  reproduction.  Irish  potatoes  are  very  generally 
grown  from  tubers,  but  they  ^vill  occasionally  produce  seeds,  and 
the  vv^ild  potatoes  of  South  America  produce  seeds  very  freely. 
The  growing  of  bulbs  of  ornamental  plants  is  a  leading  industry 
in  many  parts  of  the  world.  Holland  is  one  of  the  greatest  of 
the  bulb-producing  countries  of  the  world. 

Many  aerial  stems  reproduce  by  runners  and  offsets  and  we 
depend  largely  upon  this  method  of  reproduction  to  secure 
plants  for  agricultural  purposes.  This  is  the  regular  method 
of  propagating  strawberry  plants.  Branches  of  many  plants 
when  set  in  the  soil  will  produce  roots  and  grow  rapidly,  and  in 
nature  broken  branches  of  willows  and  many  other  plants  catch 
in  the  soil  or  become  partially  covered  and  grow.  We  have 
taken  advantage  of  this  tendency  and  propagate  many  useful 
plants  from  cuttings. 

The  art  of  budding  and  grafting  is  based  on  this  tendency  of 
cuttings  to  grow  under  favorable  conditions.  Budding  consists 
in  setting  the  buds  of  one  plant  within  the  bark  of  another  plant, 
and  is  generally  used  in  propagating  peaches,  clierries  and  sim- 
ilar fruits.  Grafting  consists  in  setting  a  part  of  a  living  twig 
with  its  buds  from  one  tree  into  the  branch  of  another  and  is 
very  generally  used  in  propagating  apples  and  similar  fruits. 

The  structure  of  stems,  their  methods  of  gi-owth  and  the 
movements  of  the  plant  juices  through  them  will  be  taken  up 
in  a  later  chapter. 

In  the  first  chapter  we  learned  that  plants  are  made  up  of 


40 


STEMS  AND  BUDS 


but  three  primary  organs,  roots,  stems  aud  leaves,  and  that  the 
other  so-called  organs  with  which  we  are  so  familiar  are  moditi- 
catious  of  these  three.  We  have  already  studied  the  roots  and  the 
stems,  but  before  taking  up  the  study  of  the  leaves  let  us  con- 
sider the  buds  which  are  undeveloped  shoots  or  stems. 


Fig.  31. — A  newly  opened  leaf  bud  of  the  maple  and  the  same  bud  dissected  to  show 
graduation  from  scale  to  leaf. 


A  leaf  bud  consists  of  a  very  short,  undeveloped  stem  bearing 
a  compact  mass  of  minute  leaves.  (Figs.  20,  21  and  31.)  This 
stem  will  elongate  and  the  leaves  grow  to  full  size.  It  is  then 
known  as  a  stem  or  shoot  with  its  leaves. 

Flower  buds  are  those  which  develop  into  flowers,  but  we 
will  learn  later  that  flowers  are  made  up  of  modified  leaves  on 
short  stems  and  therefore,  it  is  not  necessary  to  change  our 
definition  of  a  bud.     (Chapter  V.) 

Location  and  Structure  of  Buds. — Buds  are  borne  in  the 
axils,  that  is  just  above  the  point  of  union  of  the  leaf  to  the 
stem.  In  our  northern  climates  they  are  produced  a  year  in 
advance  of  their  development  into  shoots  or  fiowers  and  remain 
over  winter  in  a  dormant  or  resting  condition.  In  temperate 
climates  the  buds  are  frequently  spoken  of  as  scaly  buds  becanse 
the  lower  or  outside  leaves  are  modified  as  scales  and  serve  to 


LOCATION  AND   STRUCTURE   OF   BUDS  41 

protect  the  true  leaves  and  flowers  within.  These  scales  never 
develop  into  true  leaves.  The  examination  of  the  buds  of  many 
of  our  plants  in  the  spring  will  show  a  gradual  graduation  from 
scales  on  the  outside  to  well-formed  leaves  on  the  inside.  (Fig. 
13.)  These  outside  scales  are  frequently  covered  with  masses 
of  plant  hairs  (trichomes)  or  with  wax  or  have  the  appearance  of 
being  varnished.  These  structures  serve  as  a  protection  against 
the  entrance  of  water  which  would  cause  great  damage,  espe- 
cially during  the  winter  season.  Many  of  the  plants  of  warm 
climates  and  some  of  the  plants  of  temperate  climates  have 
naked  or  nearly  naked  buds ;  that  is,  buds  that  have  very  little 
or  no  protection  from  the  climatic  conditions. 

Buds  are  also  classified  with  reference  to  their  location  on 
the  stem.  Those  at  the  tip  are  apical  or  terminal,  while  those 
on  the  sides  are  lateral.  Lateral  buds  may  be  opposite  or  alter- 
nate. When  lateral  buds  are  directly  in  the  angle  formed  by 
the  stem  and  leaf  they  are  axillary,  but  when  to  one  side  or  above 
they  are  called  accessory.  Buds  borne  on  other  parts  of  the 
stem,  on  the  roots  and  on  the  leaves  are  known  as  adventitious ; 
they  are  of  the  greatest  importance  in  the  propagation  of  plants 
by  cuttings. 

A  plant  cannot  produce  food  for  the  growth  of  all  of  its  leaf 
buds  into  shoots  and,  therefore,  many  buds  perish,  but  some 
of  them  remain  dormant  and  many  later  develop  into  the  well- 
known  sucker  or  water  shoots.  Such  growths  are  very  common 
on  trees  that  have  been  over-pruned,  or  broken  by  storms.  If  it 
were  possible  for  all  the  buds  to  grow,  all  our  trees  would  as- 
sume the  characters  of  very  dense  hedge  plants.  The  tendency 
of  some  plants,  such  as  the  privet  and  osage-orange,  to  produce 
a  very  large  number  of  shoots  increases  their  value  as  hedge 
plants  and  ornamentals. 

The  growth  of  shoots  from  the  buds  may  be  definite  or  in- 
definite.    The  definite  annual  growths  are  those  in  which  the 


42  STEMS  AND  BUDS 

shoots  increase  in  length  for  a  few  weeks  only  and  the  remainder 
of  the  season  is  used  for  matnring  the  wood  and  bnds.  Such 
growths  are  not  likely  to  winter-kill,  and  the  growths  of  succes- 
sive  years  can  be  readily  traced  by  the  bud  scars  on  the  stem. 
The  shoots  of  other  plants  grow  throughout  the  entire  season  and 
until  checked  by  the  cold  weather ;  they  are  known  as  iridefinite 
growths,  and  are  likely  to  suffer  from  winter  injury.  The  roses, 
lilacs,  sumac  and  ailanthus  or  tree-of-heaven  are  excellent  ex- 
amples of  this  type  of  gTowi;h. 

Underground  stems  produce  buds  at  the  nodes  in  the  same 
manner  as  the  stems  above  ground.  The  so-called  "  eyes  "  of 
the  potatoes  are  buds  which  give  rise  to  shoots.  The  bulbs  of 
many  plants,  although  usually  described  as  stems,  are,  in 
reality,  buds. 

EXERCISES   WITH   STEMS   AND   BUDS 

1.  Study  of  Woody  Twigs. — Cut  a  branch  from  a  maple,  linden,  horse 
chestnut  or  other  dicotyledonous  tree  and  note  the  nodes  and  internodes 
of  the  newest  growth  as  marked  by  buds  and  scales ;  trace  as  many  seasons 
of  growth  as  possible,  beginning  with  the  tip  of  the  twig.  Examine  the 
bark  with  a  hand  lens  and  note  leaf  scars,  lenticles  and  other  peculiarities. 

2.  Monocotyledonous  Stems. — Examine  a  corn  stalk,  grass  stem, 
grain  straw  and  other  monocotyledonous  stems  and  compare  with  a  woody 
stem  studied  in  previous  exercise. 

■'>.  Cross-section  of  Herbaceous  Stem. — Cut  through  a  Begonia  stem 
(dicotyledonous),  examine  with  a  hand  lens  and  note  (a)  the  central  mass 
or  pith  surroiuided  by  (b)  a  circle  of  wedge-shaped  areas  which  are  fibro- 
vascular  bundles  of  wood,  and  which  are  separated  from  each  other  by 
material  like  the  pith  and  known  as  medulkiry  rays.  Outside  the  fibro- 
vascular  bundles  is  another  zone  which  is  in  turn  surrounded  by  the 
epidermis  or  harJ:  covering. 

4.  Layers  of  Bark. — ^Take  the  last  season's  growth  of  a  lilac,  horse- 
chestnut  or  maple.  Gently  scrape  oil  the  outer  brown  bark,  the  inner 
green  bark  and  the  fibrous  bark  and  examine  with  a  hand  lens  and  note, 
(a)  the  outer  bro\\TX  baik  layer,  (b)  the  second  or  dark  green  layer  of 
new  bark  and   (c)   the  third  layer  of  tough  fibrous  bark  or  bast. 

.'>.  Cross-section  of  Woody  Twigs. — Cut  through  a  woody  twig  of 
oak   or   basswoful   and   note    (a)    tlie   central    pith    surrounded   bj^    (b)    the 


EXERCISES  WITH  STEMS  AND  BUDS  43 

wedge-sliaped     fibro- vascular     huiulles     separated     l)y     {(■)     the     radiating 
medullary  rays  and    {d)   the  concentric  circles  or  annular  rings. 

0.  The  Parts  in  Large  Timber. — Examijie  the  cut  end  of  a  large 
stem  or  tree  trunk  and  note  the  same  points  as  in  the  preceding  exercise. 
Examine  the  enda  of  sawed  timber  and  determine  the  above  parts.  Trace 
them  in  the  long  section  of  the  timber. 

7.  Rise  of  Sap  in  Stems. — Stand  tlie  freshly  cut  stems  of  Begonia, 
liorse-chestnut  and  other  plants  in  water  colored  with  eosin  or  red  ink 
for  30  minutes,  one  hour,  and  for  24  hours.  Cut  off  small  pieces,  beginning 
at  the  base  and  examine  with  a  hand  lens.  Note  the  part  through  whicii 
the  colored  fluid  rises  and  tlie  height  to  which  it  has  risen. 

8.  Persistent  Upward  Tendency  of  Stems. — Take  an  upright,  pot- 
ted plant  and  place  in  a  horizontal  position  (pot  and  all).  Make  a  dia- 
gram to  denote  the  relative  position  of  the  parts  and  examine  again  at  the 
end  of  24  and  4S  hours. 

9.  Datndelion  Stem  and  Buds. — Examine  the  short  stem  of  the  dan- 
delion or  similar  plant.  Count  the  number  of  Imds  you  can  find  near  tlie 
surface  of  the  soil.  Does  the  number  vary  with  the  size  and  age  of  the 
plant?  Split  the  entire  plant  lengthwise  and  try  to  determine  point  of 
union  between  stem  and  root. 

10.  Examine  the  under-ground  stem  of  Solomon's  seal,  May-apple, 
Johnson  grass  or  similar  plants  and  compare  with  an  aerial  stem. 

11.  Examine  the  bulbs  of  crocus,  tulip,  gladiolus,  Indian  turnip, 
onion,  etc.,  and  note  their  general  character.  Cut  them  open  lengthwise 
and  note  the  short  stems  and  scale-like  leaves. 

12.  Examine  a  potato  tuber  and  note  its  general  character.  Note  the 
arrangement  of  the  eyes  or  buds.  Compare  with  the  fleshy  root  of  a  sweet 
potato.  Cut  through  it  and  note  the  fibro-vascular  bundles  just  beneath 
the  epidermis  or  peeling. 

13.  Buds  of  Twigs. — Examine  the  stems  of  lilac,  horse-chestnut, 
hickory  and  maple.  Note  number,  arrangement  and  relative  sizes  of  the 
buds  on  the  different  stems  and  on  the  same  stem. 

14.  Structure  of  Buds. — Take  the  large  buds  of  the  lilac,  horse- 
chestnut,  hickory,  etc.,  and  carefully  dissect  by  successively  removing  the 
scales  and  inner  parts.  Note  the  gradual  transition  from  scales  to  leaves. 
Note  the  short,  conical,  undevelo[)ed  stem  to  which  tliey  are  attached. 
Compare  the  bud  to  a  scaly  bulb.  (This  study  is  most  satisfactory  if 
conducted  in  the  early  spring  when  the  buds  are  swollen.  In  winter  the 
stems  should  stand  in  water  a   few  days  before  the  study.) 

15.  Opening  of  Buds. — Cut  a  few  of  tlie  newest  and  most  vigorous 
shoots  from  a  lilac  in  winter  or  early  in  the  spring  before  tlie  buds  open  and 
place  in  water  in  a  warm  room.  Examine  from  day  to  day  and  note  the 
opening  of  the  buds  and  growth  of  new  shoots. 


44  STEMS   AND   BUDS 

QUESTIONS 

1.  What  is  the  stem? 

2.  What  are  nodes?     Internodes? 

3.  Name  and  explain  the  types  of  stems. 

4.  Describe  a  cross-section  of  each. 

5.  Describe  the  outside  coverings  of  a  stem. 

6.  What  are  tlie  annual  rings  ? 

7.  What  are  the  differences  between  herbaceous  and  woody  stems? 

8.  What  do  you  understand  by  acaulescent?     Excurrent?     Decumbent? 
Prostrate  ? 

9.  Explain  the  methods  by  which  plants  climb. 

10.  How  can  you  distinguisli  underground  stems  from  roots? 

11.  Describe  a  rhizome.     A  bulb.     A  tuber.     Give  examples  of  each. 
12  What  are  len tides? 

13.  What  are  the  various  functions  of]  stems? 

14.  Read  and  give  a  report  of  the  flower  industry  of  Holland. 

15.  Read  and  give  a  report  of  the  history  of  the  potato. 

10.  Explain  the   natural   methods  of   plant  propagation   by   means  of 
stems. 

17.  What  are  the  artificial  methods  of  plant  reproduction  by  stems? 

18.  Compare  a  corn  stalk  with  the  stem  of  a  woody  plant. 

19.  What  are  medullary  rays? 

20.  Through  what  part  of  the  stem  does  water  rise?  How  demonstrated? 

21.  When    you    examine   the    cut   end    of    a    large    woody    stem   what 
do  you  see  ? 

22.  What  occurs  when  planta  are  exposed  so  as  to  receive  the  sun  on 
one  side  only? 

23.  What  is  the  general  direction  of  stem  growth  as  compared   with 
root  growth  ? 

24.  \Miere  do  you  find  the  fibro-vascular  bundles  in  the  tuber  of  the 
Irish  potato? 

25.  Compare    the    tuber   of    the    Irish    potato    with    the    root    of    the 
sweet  potato. 

2G.  What  is  a  bud? 

27.  What  is  a  flower  bud? 

28.  Where  are  buds  borne? 

29.  When  are  buds  produced  ? 

30.  What  do  you  understand  by  apical,   lateral,   opposite,   alternate, 
axillary,  accessory  and  adventitious  buds? 

31.  Do  all  the  leaf  buds  grow  into  shoots?     Whyl 

32.  What  do  you  mean  by  definite  and  indefinite  growths? 

33.  What  are  the  eyes  of  the  potato  tuber? 


CHAPTER  IV 
LEAVES 

The  leaves  of  a  plant  are  always  borne  on  the  stem  and  have 
the  same  relative  position  as  the  buds.  (Figs.  20  and  21. )  They 
are  the  expanded  parts  of  the  plant  and  have  a  definite  rela- 
tionship to  the  air  and  simlight. 

Green  plants  must  have  an  expanded  surface  (usually  the 
foliage)  into  which  the  gaseous  elements  (Chapter  X)  of  the 
air  may  pass.  These  gaseous  elements  are  as  necessary  for  the 
growth  of  the  plant  as  are  the  raw  food  materials  of  the  soil. 
These  expanded  parts  contain  chlorophyll  or  the  green  coloring 
material  which  is  necessary  for  the  formation  of  true  food  sub- 
stances from  the  elements  and  compounds  obtained  from  the 
water,  soil  and  air. 

Relation  to  Light. — If  you  stand  under  a  tree  and  look 
upwards,  you  will  note  that  the  leaves  are  on  or  near  the  tips  of 
the  twigs  and  thus  form  a  canopy  or  tent  with  the  trunk  and 
branches  as  the  supporting  framework.  If  you  place  yourself 
in  such  a  position  as  to  look  down  upon  a  small  tree  or  other 
plant  or  at  a  vine  (Fig.  32),  climbing  over  a  wall  you  will  be 
surprised  to  note  how  very  little  the  leaves  shade  one  another, 
and  that  all  have  very  nearly  the  same  light  and  air  exposure. 
The  leaves  of  many  plants,  especially  the  legumes,  are  also 
raised  and  lowered  to  some  extent  throughout  the  day  in  such 
a  manner  as  to  receive  the  sunlight  to  the  best  advantage. 

The  leaves  are  the  factories  in  which  the  raw  food  sub- 
stances are  transformed  into  true  food  substances  for  the  growth 
of  the  plant.  The  water  and  these  various  raw  or  crude  food 
substances  which  may  be  dissolved  in  it  are  taken  from  the  soil 

45 


46 


LEAVES 


and  carried  to  the  leaves  where  the  most  of  the  water  is  trans- 
pired into  the  air.  (Page  114.)  The  leaves  take  carbon  dioxide 
gas  (CO2)  from  the  air  and  as  a  result  of  the  action  of  the  sun- 
light on  the  green  coloring  matter  (chlorophyll)  these  sub- 
stances are  transformed  into  starch.     This  process  is  known  as 


Fig.  32. — Ivy  leaves  on  a  wall  showing  the  arrangement  with  very  little  overlapping. 

photosynthesis  (Page  11 T)),  which  is  the  most  remarkable 
process  in  all  nature.  It  is  the  most  important  process  in  plant 
gi'owth,  and  without  plant  life  there  could  be  no  animal  life. 
Sunlight  and  Chlorophyll. — The  formation  of  the  complex 
food  substances  or  compounds  from  the  crude  materials  of  the 
soil  and  air  is  accomplished  in  green  plants  only  and,  there- 


SUNLIGHT  AND  CHLOROPHYLL 


47 


fore,  all  animals  and  all  plants  that  do  not  contain  chlorophyll 
are  dependent  either  directly  or  indirectly  upon  these  green 
plants  for  their  food  supply.  Different  kinds  of  plants  require 
varying  amounts  of  light  and,  therefore,  we  find  some  plants 
growing  in  the  direct  sunlight,  while  others  are  usually  found  in 
the  shade  and  will  not  thrive  in  the  intense  sunlight.  We  also 
notice  that  the  arrangement  of  tlie  foliage  on  the  plant,  and  its 


Fig.  33.— Self-pruned  twigs  of  the  poplar  showing  the  cleavage  planes. 

position  during  different  hours  of  the  day  and  on  cloudy  and 
clear  days,  are  such  as  to  relieve  the  sunlight  in  proportions  more 
or  less  suitable  for  its  own  work.  Plants  gTowing  in  the  desert, 
or  other  dry  places,  may  be  "  leafless  "  or  have  the  leaves  greatly 
reduced,  but  the  stems  of  such  plants  contain  the  chlorophyll 
and  serve  as  foliage.  Plants  may  produce  more  foliage  than  is 
necessary  for  their  normal  growth.  Rueh  plants  may  drop  in- 
dividual leaves  or  even  large  shoots  during  the  growing  season 
by  a  process  of  self-pruning.     These  leaves  and  shoots  are  not 


48 


LEAVES 


broken  off  but  "  grow  off  "  by  the  formation  of  definite  cleav- 
age planes  as  in  the  shedding  of  leaves  for  winter.  This  self- 
pruning  process  is  very  common  among  willows,  poplars,  cotton- 
woods  and  many  other  trees.     (Fig.  33.) 

Parts  of  Leaves. — A  simple,  typical  leaf  (Fig.  34)  has  a 
blade  or  lamella  supported  by  a  framework  composed  of  libs 


Fig.  34. — Simple  net-veined  leaf. 


Fig.  35. — Simple  parallel-veined   leaf. 


and  veins.  The  principal  rib  is  known  as  the  midrib  and  is  a 
continuation  of  the  leaf  stem  or  petiole.  Leaves  which  do  not 
have  petioles  are  sessile.  These  ribs  and  veins  are  continuations 
of  the  woody  bundles  found  in  the  stems  and  serve  not  only  to 
support  the  leaf  but  as  channels  through  which  the  water  and  raw 
food  materials  pass  to  the  leaf,  and  through  which  more  com- 
plex food  substances'  pass  to  other  parts  of  the  plant.  Minute 
structures,  known  as  stipules,  frequently  are  found  at  the  bases 
of  the  petioles.  They  are  extremely  variable  in  form  and 
character.  Sometimes  they  are  leaf-like  and  may  fall  soon  after 
the  unfolding  of  the  leaves  as  in  the  willows ;  sometimes  they  are 


TYPES  OF  LEAVES 


49 


attached  aloi;g  the  margin  of  the  petioles  as  in  the  clovers; 
sometimes  they  are  developed  as  sheaths  enclosing  the  stem  as 
in  the  grasses  and  grains  ;  and  sometimesi  they  enclose  the  young 
leaves  as  in  the  tulip  tree. 

Types  of  Leaves, — Leaves  which  have  one  prominent  mid- 


1. — Palniately  veined  leaf 


Fig.  37. — Palmately  veined  leaf. 


rib  running  from  base  to  apex,  and  giving  rise  to  numerous  side 
branches  with  smaller  veinations  between  them  are  said  to  be 
net-veined  (Fig.  34),  while  leaves  which  have  a  number  of 
equally  prominent  veins  running  from  base  to  tip  are  said  to 
be  parallel-veined.  (Fig.  35.)  Most  dicotyledonous  plants 
have  net-veined  leaves,  while  most  monocotyledonous  plants 
have  parallel-veined  leaves.  Leaves  which  have  three,  five  or 
more  prominent  ribs  or  veins  arising  from  a  common  point  are 
said  to  be  palmate-net-veined  or  radiate-net-veined  (Figs.  36 
and  37),  while  those  that  have  numerous  veins  arising  from  a 
main  mid-rib  are  said  to  be  pinnate-net-veined  or  feather-net- 
veined.     (Fig.  34.) 


50 


LEAVES 


Compound  Leaves. — Leaves  which  are  composed  of  two  or 
more  leatiets  arising  from  a  single  petiole  are  said  to  be  com- 
pound and  are  described  as  iMlmale-  or  radiate-compound  (Fig, 
38),  or  as  pinnate-  or  feather-compound.  (Fig.  39.)  The  size, 
form,  arrangement  and  various  other  modifications  of  the  leaves 
of  plants  are  largely  dependent  upon  the  environmental  factoi'S, 


Fig.  38. — Palmately  compound  leaf. 


Fig.  39. — Pinnately  compound  leaf. 


especially  light  and  moisture.  Land  plants,  growing  in  very 
wet  surroundings  tend  to  have  larger  leaves  than  those  growing 
in  dry  or  arid  surroundings.  Aquatic  plants  in  running  water 
tend  to  have  long,  narrow  leaves  as  compared  with  plants  living 
in  still  water. 

The  Leaf  Blade. — The  veination  of  the  leaves  supports  a 
delicate  structure  (Page  102),  within  which  are  numerous  air 


USES   OF   LEAVES  51 

passages  with  openings  (stoniata)  to  the  outside,  usually  on  the 
lower  surface.  These  passages  and  openings  facilitate  the  trans- 
piration of  water  (Page  H-i),  and  the  absorption  of  gases. 
(Page  115.)  The  texture  of  leaves  varies  largely  with  the  en- 
vironment in  which  they  live.  The  surfaces  of  leaves  are  also 
frequently  covered  with  spines,  hairs  (trichomes),  gland  hairs, 
wax,  etc.,  which  serve  to  protect  the  plant,  prevent  excessive 
transpiration  and  otherwise  facilitate  its  work. 

Uses  of  Leaves. — Leaves  are  so  abundant,  and  come  with 
such  great  regularity  that  we  are  likely  to  fail  to  appreciate  their 
importance  in  the  life  of  the  plant.  But  these  very  common- 
place facts  should  convince  us  that  they  are  invaluable  to  the 
plant,  that  they  are  something  more  than  elements  of  beauty 
in  the  individual  plant  or  in  the  landscape.  We  have  already 
learned  that  the  primary  function  of  leaves  is  to  serve  as 
foliage  through  which  the  living,  growing  plant  receives  gases 
from  the  air  and  energy  from  the  sun  and  in  which  the  raw 
food  substances  are  transformed  into  true  foods  (photosyn- 
thesis, Page  115).  But  the  leaves  serve  many  other  useful  pur- 
poses which  are  important  in  the  life  history  of  the  plant:  (a) 
they  are  the  organs  of  transpiration  (Page  ll-l),  by  which  are 
given  off  quantities  of  water  previously  absorbed  through  the 
roots;  (h)  they  are  organs  of  respiration,  although  this  func- 
tion is  not  confined  to  the  leaves;  (c)  they  may  serve  as  bud 
scales  for  the  protection  of  the  more  typical  foliage  leaves  and 
flowers  (Page  40)  ;  (d)  they  may  develop  a  bitter  gnim  and 
thus  serve  as  a  protection  against  birds  and  other  small  animals 
which  feed  on  the  new  growths  in  the  early  spring;  (e)  or  they 
may  develop  as  briars  or  thorns  which,  no  doubt,  serve  to  some 
extent  as  a  protection  against  larger  animals.  Thistles  and  other 
plants  which  are  armed  with  these  protective  structures  will 
stand  unmolested  in  the  stock  pasture,  even  though  the  food 


62  LEAVES 

supply  for  the  cattle  may  be  very  limited.  Every  good  farmer 
knows  the  advantage  of  using  sheep  or  goats  for  the  cleaning 
of  neglected  lands  of  these  anued  weed  pests  which  most  live-- 
stock will  not  touch. 

Leaves  also  serve  for  the  storage  of  food  and  water  as  in 
the  case  of  the  so-called  "  century  plant,"  which  grows  for  a 
number  of  years  and  then  develops  its  flowers  and  seeds  at  the 
expense  of  the  food  stored  in  the  large  fleshy  leaves.  This  is 
no  more  wonderful  than  the  common  cabbage  in  which  exactly 
the  same  thing  occurs  in  a  cycle  of  two  years ;  the  accumula- 
tion of  the  food  is  during  the  first,  and  producing  the  flower 
and  seed  during  the  second  year.  Man  has  taken  advantage  of 
this  tendency  of  the  plant  to  store  its  food  in  the  leaves  and 
makes  \ise  of  many  such  plants  as  food  for  himself.  Leaves  may 
also  serve  for  the  storage  of  air  as  in  the  case  of  the  floating- 
plants  which  contain  large  air-chambers. 

In  some  few  plants  the  leaves  have  undergone  modifications, 
enabling  them  to  serve  as  insect  traps  for  the  capture  of  insects 
which  die,  decay,  and  furnish  a  supply  of  nitrogenous  food  for 
the  growing  plant.  The  most  interesting  insect  catchers  are  the 
sun-dew,  Ven\is  fly-trap,  and  the  pitcher  plants,  which  you 
will  find  described  in  an  encyclopedia,  and  in  many  works  on 
botany. 

Probably  the  most  important  function  of  leaves  after  photo- 
synthesis is  the  formation  of  flowers  and  fruits,  for  as  we  shall 
learn  later,  the  flowers  are  modified  leaves.     (Page  54.) 

EXERCISES 

1.  Collect  the  followin»  forms  of  leaves:  simple  net- veined,  simple  par- 
allel-veined, simple  palmate-veined,  compound  palmate-veined  and  com- 
pound pinnate-veined.     Make  drawings  and   label   the  parts. 

2.  Collect  and  make  drawings  of  leaves  with  and  without  petioles. 

3.  Collect  leaves  showing  different  types  of  stipules. 


QUESTIONS  53 

QUESTIONS 

1.  On  wliat  part  of  the  plant  are  tlie  leaves  boine? 

2.  Why  is  it  necessary  that  the  leaves  should  be  exj)osed  to  the  air? 

3.  What  are  the  sources  of  plant  food? 

4.  Why  is  it  necessary  that  the  plant  receive  sunlight? 

5.  Why  are  animals  dependent  on  plants  for  food? 

6.  Are  there  any  other  sources  from  which  animals  can  secure  food? 

7.  What  parts  of  the  plant  other  than  the  leaves  may  possess  chlor- 
ophyll?   Give  examples. 

8.  Name  the  parts  of  a  simple  leaf. 

9.  What  are  the  differences  between  net-  and  parallel-veined  leaves? 

10.  Wliat  are  the   differences   between   simple  and   compound    leaves? 
Give  examples  of  each. 

11.  What  are  the  functions  of  the  leaves? 


CHAPTER  V 

THE  FLOWER 

Having  studied  the  three  primary  parts  of  the  pUant,  the 
root,  stem  and  leaves,  we  now  turn  our  attention  to  the  most 
important  secondary  organ,  the  flower.  The  flowers  of  many 
plants  are  objects  of  beauty,  but  the  great  majority  of  plants 
bear  flowers  which  are  very  small  and  inconspicuous,  or  which 
are  of  such  character  that  they  do  not  attract  the  attention  of 
the  casual  observer.  Many  people  are  so  accustomed  to  think- 
ing of  flowers  as  mere  objects  of  beauty  that  they  fail  to  realize 
the  very  great  importance  of  these  organs  in  the  life  history  of 
the  plant.  The  flowers  contain  the  sexual  organs  of  the  plant 
and  are  necessary  for  the  production  of  seeds  and  fruits. 

Parts  of  the  Flower. — The  flower  does  not  present  any  new 
structures,  but  is  a  shortened  stem  bearing  circles  of  leaves, 
which  have  been  greatly  modified  in  shape  and  color  into 
parts  constituting  the  flower.  Instead  of  being  borne  on  a 
long  stem,  they  are  now  brought  together  in  circles  and  the 
shortened  stem  is  known  as  the  receptacle,  or  torus;  the  first  or 
outer  circle,  composed  of  parts  which  are  usually  green  and 
resembling  ordinary  leaves,  is  known  as  the  calyx,  and  each 
leaf-like  part  is  called  a  sepal;  tlio  second  circle  or  series  of 
circles  composed  of  parts  which  also  have  some  resemblance 
to  leaves  but  which  are  usually  colored  is  known  as  the  corolla, 
and  each  part  is  called  a  petal;  the  third  set  of  organs  consisting 
of  one  or  more  circles  is  composed  of  stamens  which  bear  very 
little  resemblance  to  leaves;  the  last  or  central  group  consist- 
ing of  one  or  more  organs  which  may  be  distinct  or  united  is  the 
pistil  which  also  bears  very  little  resemblance  to  leaves.  (Figs. 
54 


PARTS  OF  THE  FLOWER 


55 


40  to  44.)  The  calyx  and  corolla  constitute  the  floral  envelope 
or  perianth  while  the  filamois  and  pistils  are  the  sexual  or  essen- 
tial organs  of  the  phmt.  The  arrangement  of  the  organs  in 
circles  permits  the  making  of  diagrams  which  represent  the 
general  plan  of  a  Hower  as  clearly  as  a  map  shows  the  physical 


FiQ.  40. — a,  cherry  blossom;  b  and  c,  diagrams  showing  the  arrangement  of  the  parts. 


FiQ.  41. — a,  diagrammatic  longitudinal  section  of  apple  blossom;  b  and  c,  peach  bloBSom. 


and  political  divisions  of  the  earth.  If  this  diagram  is  accom- 
panied by  a  second  diagram  made  at  right  angles  to  the  first, 
the  general  architecture  of  the  flower  is  well  shown. 

The  sepals  and  petals  being  leaf-like  in  character  sometimes 
grade  imperceptibly  the  one  into  the  other.  In  some  flowers,  of 
which  many  lilies  are  examples,  the  parts  of  these  outer  circles 


56 


THE  FLOWER 


are  practically  alike  in  both  shape  and  color;  while  in  other 
flowers  there  is  no  corolla.  When  the  corolla  is  missing,  the 
calyx  may  be  green,  but  it  is  usually  of  some  other  color  which 
deceives  many  observers  into  believing  it  to  be  the  corolla.  The 
common  hepatica  and  the  wind  flower  are  good  examples  of 
flowers  with  colored  calyx  and  no  corolla. 

When  the  corolla  alone  is  absent,  the  flower  is  described 
as  apetalous  {i.e.,  without  petals).     Some  plants  have  flowers 


Fig.    42. — Diagrammatic   drawing  and  cross-section    of  a  lily. 
Fig.  43. — Diagrammatic  longitudinal  and  cross-sections  of  a  pea  blossom. 

with  neither  calyx  nor  corolla,  but  these  incomplete  flowers  are 
just  as  important  in  the  life  history  of  the  plant  as  the  very 
complicated  and  highly  colored  flowers  of  other  species. 

The  stamens  in  most  flowers  are  distinct  and  have  no  external 
resemblance  to  leaves,  but  in  some  flowers  the  gradual  transi- 
tion from  petals  to  stamens  is  so  apparent  as  to  leave  no  doubt 
whatever  as  to  origin,  even  in  the  mind  of  the  most  casual 
observer.  This  is  especially  well  illustrated  in  the  white  water 
lilies.  In  a  state  of  nature,  we  sometimes  find  flowers  in  which 
the   petals   assume  stamen  character  or  the   stamens  tend  to 


FLOWER  TYPES 


57 


become  petal-like  in  ciiaracter.  This  teiideucy  in  plants  makes 
it  possible  for  the  Horist  to  develop  double  flowers  from  the 
natural  single  ones ;  the  wild  rose  has  but  five  petals,  and 
numerous  stamens,  but  the  double  rose  has  many  petals  and  few 
or  no  stamens,  they  having  been  transformed  into  petals,  more 
or  less  like  the  other  petals. 

The   pistils  are  more  distinct  than  the  stamens  but   will 
sometimes  assume  petal-like  characters.     The  organs  of  some 


—  S 


Fig.  44. — a,  twig  and  two  clusters  of  elm  blossoms;    b  and  c,  diagrammatic  longitudinal  and 
cross-sections  of  a  single  blossom. 

flowers  are  imperfect  and  of  no  use  to  the  plant.  If  all  of  the 
stamens  or  all  of  the  pistils  are  imperfect  the  plant  cannot 
produce  seeds  and,  therefore,  must  be  propagated  by  some 
method  other  than  by  seeds.  This  will  be  explained  later. 
(Chapter  VI.) 

Flower  Types. — A  flower  which  is  composed  of  the  four  sets 
of  organs  is  said  to  be  compleie  (Fig.  40),  and  a  flower  pos- 
sessing both  stamens  and  pistils,  regardless  of  the  presence  or 
absence  of  calyx  and  corolla,  is  said  to  be  perfect.  (Fig.  40.) 
A  flower  in  which  the  number  of  organs  in  each  set  is  the  same 
or  a  multiple  of  the  same  is  symmetrical.     (Figs.  42  and  43.) 


58 


THE  FLOWER 


If  all  of  the  organs  of  each  set  are  the  same  sizel  and  shape  it 
is  regular,  (i'ig.  40.)  The  opposites  of  the  ahove  are:  incom- 
plete, imperfect,  unsymmetrical  and  irregular.  The,  apple, 
peach  and  cherry  (Figs.  40  and  41)  are  complete  and  perfect; 

the  lily  (Figs.  42  and  51)  is 
symmetrical  and  regular ; 
the  com  (Figs.  46  and  48) 
and  castor  oil  plant  are  both 
incomplete  and  imperfect ; 
the  apple  and  j)each  nnsym- 
metrical ;  the  violet  and  bean 
(Fig.  47)  irregular. 

Imperfect  Flowers. — 
Some  plants  bear  two  kinds 
of  imperfect  flowers,  those 
with  stamens  which  are 
known  as  staminate  flowers, 
and  those  with  pistils  which 
are  known  as  pistillate  flow- 
ers. In  some  cases  the  two 
sets  of  flowers  are  so  different 
in  general  appearance  as  to 

Fig.  45.— Single  blossom  of  rye;  a,  stamen;  o,       be  rcadilv  distinguished  while 
pistil.  .  "^ 

m  other  cases  they  are  very 
much  alike  and  cannot  be  distingiiished  except  by  a  more  care- 
ful examination.  Plants  which  bear  these  two  kinds  of  imperfect 
flowers  are  said  to  be  monoecious  (Figs.  46  and  48),  i.e.,  of  one 
household.  The  common  corn  is  a  good  example  of  a  mon- 
oecious plant,  the  tassel  being  composed  of  staminate  flowers 
while  each  grain  with  a  single  thread  of  silk  is  a  pistil.  Each 
mature  grain  of  corn  is  a  fniit  produced  from  a  single  pistil- 
late flower. 

Other  plants  bear  the  staminate  and  pistillate  flowers  on 
difl"erent  individuals  and  are  knovra  as  dia'cious  (i.e.,  of  separate 


IMPERFECT  FLOWERS 


59 


? 


Fig.  46. — Two  ears  of  Indian  corn;  i.e.  the  pistillate  flower. 

households).  The  mulberry,  willow  and  poplar  are  excellent 
examples  of  dioecious  plants.  The  fruits  of  these  plants  are 
always  borne  on  the  pistillate  plants. 


60 


THE  FLOWER 


lu  the  examination  of  a  largo  number  of  plants  we  will  find 
many  interesting  modifications  of  strictly  monoecious  and  di- 
oecious types.  The  Indian  turnip  or  Jack-in-the-pulpit  (Fig. 
49)  is  usually  dioecious,  but  many  plants  will  be  found  which 
are  monoecious.  Some  species  of  plants,  of  which  the  maples 
are  good  examples,  both  bear  perfect  and  imperfect  flowers,  while 
individuals  are  frequently  found  which  do  not  bear  flowers 
of  any  kind. 


4^^000^ 


Fig.  47. — LpRume   blossom;    a  and  I),  the  hlossoiu;  c,  the  blossom  dissected  showing  the 
petals;  d,  the  sepal,  stamen  and  pistil;  e,  the  mature  seed  pod. 

Modified  Calyx  and  Corolla — Both  the  calyx  and  the  cor- 
olla are  frequently  modified.  The  simplest  modification  is 
the  union  or  partial  union  of  the  sepals  or  petals  or  both  to 
form  tubes.  Flowers  in  which  these  unions  occur  are  described 
as  gamo-sepalous  and  gamo-petaJous  (Fig.  50),  while  those  in 
which  there  is  no  union  are  described  as  poly-petalous  and  poly- 
sepalous.  (Figs.  40,  42,  43  and  51.)  The  petals  and  sepals  may 
also  be  modified  to  form  spurs,  as  in  the  violet,  or  in  many  other 
ways.  The  calyx  and  corolla  are  borne  on  the  receptacle,  but 
in  some  cases  the  corolla  appears  to  be  attached  to  the  calyx. 
We  will  find  these  numerous  modifications  of  very  great  inter- 
est, and  they  are  of  very  great  importance  in  the  life  history  of 


PARTS  OF  THE  STAMENS 


61 


Fig.  48. — The  tassel  ur  staininate  flowers  of  the  Indian  corn. 


the  plant.  This  question  will  l)o  taken  u])  more  fully  on  page  80. 
Parts  of  the  Stamens.— An  ordinary  stamen  (Fig.  40)  con- 
sists of  two  very  distinct  parts,  the  filament  or  stem,  which 
corresponds  to  the  petiole  and  midrib  of  a  leaf,  and  the  anther, 
at  the  tip,  which  corresponds  to  the  blade  rolled  or  modified  so 


62 


THE  FLOWER 


as  to  form  small  sacs  containing-  a  delicate  powder,  known  as 
pollen.    The  stamens  also  present  different  forms  in  the  various 
plants.     They  are  usually  borne  on  the  receptacles,  but  some- 
times appear  to  be  attached   to  other   parts.      They  are  fre- 
quently   united    into    groups 
and  in  some  plants  in  such 
a  manner  as  to  form  a  tube 
enclosing    the    pistil.       The 
little  pollen  sacs  have  differ- 
ent     methods      of      opening 
which   may   be  readily   seen 
with  the  hand  lens  and  which 
will  prove  very  interesting  to 
the  close  observer.     The  pol- 
len is  very   important,      No 
two  plants  have  exactly  the 
same  kind  of  pollen.     It  var- 
ies in  size,  shape  and  struc- 
ture.   The  study  of  the  pollen 
of  various  flowers  under  the 
microscope   is   very   interest- 
ing.    It  is  carried  by  wind 
and  water,  and  sometimes  by 
other    means    to    the    pistil, 
where  it  undergoes  a  growth 
which  will  be  described  later. 
(Chapter  VI,) 
The  Pistil.- — There  may  be  one  or  more  pistils.     (Fig.  40.) 
If  one,  it  may  represent  one  or  it  may  represent  many  united 
leaves.     Where  there  are  two  or  more  pistils,  they  may  be  en- 
tirely separate  or  they  may  be  partly  united.    The  pistil  is  com- 
posed of  an  ovary  or  basal  part  containing  the  ovules,  which 
are  to  become  seeds;  a  style,  which  varies  in  length  in  different 
plants;  and  a  stigma,  which  is  the  only  part  of  the  plant  not 


Fig.  49. — Indian  turnip  or  Jack-in-t he- 
pulpit;  a,  bulb;  b,  leaf  and  spathe;  c,  spathe 
open    to  show   spadrix   and   flower   near   the 


THE  PISTIL  63 

covered  with  an  epidermis  or  skin.  The  pistils  are  also  subject 
to  many  moditications,  but  are  always  borne  on  the  receptacle. 
However,  if  the  other  organs  originate  below  the  ovary,  it  is 
said/  to  be  superior  (as  in  the  peach  flower),  but  if  they  origin- 
ate above  it,  it  is  said  to  be  inferior  (as  in  the  apple  blossom). 
The  arrangement  of  the  organs  in  the  flower  can  be  described 
by  three  tei-ms:  liypogynous  (Fig.  4-i),  the  simplest  form, 
in   which   the   sepals,    petals,    and   stamens   arise  from   below 


Fig.  50. — Squash  blossoms.    A  gamopetalous  flower. 

the  carpels;  perigynous  (Fig.  40),  in  which  the  receptacle  is 
extended  into  a  cup-like  structure  about  the  carpels  and  bearing 
the  sepals,  petals  and  stamens  on  its  rim  and  frequently  more 
or  less  united  at  their  bases ;  and  epigynous,  in  which  this  cup 
envelops  the  ovary,  thus  giving  the  true  inferior  ovary. 

The  modified  leaves  of  which  the  pistil  is  composed  are 
frequently  called  the  carpels,  and  the  point  of  attachment  of 
the  ovules  is  called  the  placentae.  The  placentse  may  be  either 
central  or  parietal  {i.e.,  on  the  sides  of  the  ovary).  The  num- 
ber of  carpels  can  usually  be  determined  by  cutting  a  cross  sec- 
tion of  the  ovary  and  examining  with  a  hand  lens ;  the  number  of 
carpels  being  represented  by  the  number  of  fibrous  bundles 
which  correspond  to  the  midribs  of  the  leaves  of  which  the 


64  THE   FLOWER 

pistil  is  composed.  The  number  of  carpels  does  not  necessarily 
correspond  with  the  number  of  chambers  in  the  ovary.  Of 
course,  it  will  be  readily  recognized  that  the  ovary  eventually 
becomes  the  seed  case  of  a  dry  fruit  and  that  it  is  also  an  im- 
portant factor  in  the  formation  of  fleshy  fruits. 


Fig.  51. — Lily  blossom.  A   polypetalous  flower. 

Flower  Clusters. — The  arrangement  of  flowers  on  the  stem 
is  called  the  inflorescence.  A  few  of  the  most  common  types 
of  inflorescence  are  as  follows:  (1)  The  raceme  (Fig.  52)  in 
which  a  number  of  flowers  are  borne  along  a  stem,  the  lower 
blooming  first.  The  minute  leaf  which  is  usually  at  the  base 
of  each  flower  is  called  a  bract.  (2)  The  corymb  is  a  raceme 
in  which  the  pedicels,  or  little  stems,  of  the  lower  flowers  are 
elongated  so  that  the  flowers  are  practically  on  the  same  level. 


FLOWER  TYPES 


65 


(3)  The  umhel  (Fig,  5.'])  in  which  the  pedicels  arise  from  the 
same  point  and  are  practically  the  same  length.  (4)  The  spike 
(Figs.  54,  55  and  50)  in  which  flowers  are  nnmerous,  compact 
and  sessile.  (5)  The  head  (Figs.  57  and  58),  in  which  the 
main  stem  is  shortened,  giving  rise  to  a  cluster  of  flowers  form- 
ing a  more  or.  less  definite  sphere.  (6)  The  spadix  (Fig.  49) 
in  which  the  main  stem  is  fleshy  and  the  cluster  of  flowers  en- 
veloped in  a  leaf-like  structure  called  a  spathe.  (7)  The  catkin 
in  which  the  minute  flowers  are  more  or  less  compact,  and  the 


Fig.  52. — Toad  flax  blossoms,  showing  the  open  development  of  the  blossoms. 

entire  raceme  pendant.  (8)  The  cijme  which  is  similar  to  the 
raceme,  but  which  difl'ers  from  all  of  the  preceding  by  having  the 
apical  flowers  bloom  before  the  lateral  flowers.  Finally,  there 
are  many  special  terms  which  are  used  for  describing  other 
forms  of  inflorescence,  but  which  we  will  omit  for  the  present. 

CLASSIFICATION 


Flower  Types — "Wlien  we  stop  to  think  about,  or  try  to 
count  and  record  the  many  plants  with  which  we  are  familiar, 
although  we  may  not  know  their  names,  we  find  that  we  have 
a  task  which  is  extremely  difiicult.  But  when  we  realize  that 
we  know  only  a  few  of  the  many  hundreds  of  thousands  of 
plants  of  difi^erent  kinds  which  are  distributed  over  the  face 
of  the  earth,  we  understand  that  we  must  have  some  very 
definite  system  of  classification  or  grouping  by  which  we  will 
6 


66 


THE  FLOWER 


be  euabled  to  locate  aud  record  them  and  designate  those  in 
which  we  are  most  interested.  This  system  must  be  the  same 
throughout  the  world  and  for  people  of  all  civilized  languages. 
Several  systems  have  been  suggested,  used  and  discontinued  at 
various  times  during  the  centuries  that  mankind  has  studied 

plants.  The  one  that  we  now 
use  is  known  as  the  natural 
system  and  is,  no  doubt,  better 
than  any  of  the  preceding.  By 
this  system,  we  try  to  group  or 
classify  plants  by  their  blood 
relationships  and  not  upon  the 
superficial  resemblances. 

We  readily  recognize  that 
apples,  pears  and  quinces  are 
very  much  alike.  The  foliage 
on  the  trees  is  almost  identical, 
the  flowers  have  corresponding 
parts  in  the  same  general  ar- 
rangements, and  if  we  cut  the 
fruits  we  find  that  they  have  the  same  general  characters. 

Peaches,  plums  and  cherries  form  another  well-defined 
group ;  they  also  have  flowers  and  fruits  of  the  same  character. 
l^ow  if  we  compare  one  of  the  two  groups  with  the  members 
of  the  other  we  find  that  the  flowers  of  all  are  very  similar 
except  that  in  the  ovaries  and  fruits  of  the  two  groups  they  are 
quite  difi'erent.  In  the  first  group  the  ovaries  are  inferior  and 
the  fruit  with  a  five-parted,  papery  seed  chamber,  while  in  the 
second  group,  the  ovaries  are  superior  and  have  the  one  stony 
seed  chamber. 

If  we  take  the  blackberries  and  the  raspberries  as  repre- 
senting a  third  group,  we  find  flowers  similar  to  the  preceding 
but  with  masses  of  superior  ovaries;  and  if  we  take  the  wild 


Fig.    53. — Wild     carrot      blossoms.     The 
umbel    type   of   inflorescence. 


FLOWER  TYPES  67 

rose  as  representing  a  fourth  group,  we  again  find  flowers 
strikingly  similar  to  these  groups  but  with  inferior  ovaries  that 
never  have  the  development  represented  by  the  apple. 


Fig.  54. — Sedge  or  spike  type  of  inflorescence.     Fio.  55. — Blue  grass  inflorescence. 

Now,  the  very  great  resemblance  in  all  these  gi'oups  leads 
us  to  place  them  all  in  the  one  family,  Rosacece. 

But  in  the  study  of  these  characters  we  must  make  sure  that 
the  resemblances  are  real  and  not  superficial.  The  fruits  of  the 
blackberry  and  mulberry  are  very  similar  in  general  appear- 


68  THE  FLOWER 

aiice,  but  when  we  go  back  to  the  flower  and  study  them  botan- 
ically,  we  find  that  they  are  qnite  different ;  the  fruit  of  the 
former  is  composed  of  the  many  ripened  ovaries  of  a  single 


^     "^             "^ 

%""' 

ii^r 

V\ 

^    '%. 

m\ 

\*> 

^%^ 

^ 

m 

1 

Fig.  56. — Rye  inflorescence. 


flower,  while  the  fruit  of  the  latter  is  composed  of  the  ripened 
ovaries  of  a  number  of  small  flowers. 

On  the  other  hand,  the  potato,  tomato,  pepper  and  tobacco 


FLOWER  TYPES 


69 


may  appear  quite  ditfereut,  but  an  examination  of  the  flowers 
shows  them  to  be  very  similar  and  belonging  to  one  family 
{Solenacew).  The  flowers  of  the  potato,  tomato  and  pepper  are 
very  similar ;  the  flower  of  the  tobacco  is  somewhat  difi^erent, 


Fig.  57.— Sunflower  head.   Composite  type  of  inflorescence. 


but  has  the  same  general  characters ;  the  cultivated  potato  has 
almost  the  power  of  producing  fruit,  but  when  the  fruit  is  pro- 
duced it  is  very  similar  to  a  small  tomato ;  the  fruit  of  the  tomato 
is  fleshy;  the  fruit  of  the  pepper  very  similar  but  tending  to 
become  leathery;  the  fruit  of  the  tobacco  is  of  the  same  char- 
acter but  tending  to  become  papery  in  character. 


70 


THE  FLOWER 


The  Natural  Classification  endeavors  to  grmip  plants  in 
accordance  with  trne  botanical  resemblances,  and  these  groups 
are  combined  into  larger,  nntil  we  have  the  entire  plant  king- 
dom in  four  large  groups.  Thus  far  we  have  studied  flowering 
plants  only,  but  the  plant  kingdom  includes  many  plants  which 
do  not  produce  flowers  or  seeds.  The  principal  groups  of  the 
plant  kingdom  may  be  represented  by  the  followig  outline : 


A.  Cryptogams 
(Seedless   plants) 


1.  Thallophytes 


2.  Bryophyte 


3.  Pteridophytt 


a.  Alg« — mostly  water 
plants. 

h.  Fungi  —  plants 
witliout  clilorophyll; 
moulds,  muslirooms, 
etc. 

a.  HepaticfE  — ■  Liver  - 
worts. 

b.  Musci — ^INIosses. 

a.  Ferns  and  related 
plants. 


B.  Phanerogams 
(Seed  plants) 


4.  Spermatophytes 


a.  Gymnosperms  —  cone- 
bearing  plants ;  pines, 
cedars,  etc. 

6.  Angiosperms  —  true 
flowering  plants. 


For  the  present  we  will  not  study  the  Cryptogams  or  the 
Gymnosperms,  but  will  continue  our  studies  on  the  Angiosperms 
or  true  flowering  plants.  We  have  already  learned  that  this  last 
group  is  sub-divided  into  monocotyledonous  and  dicotyledon- 
ous plants,  and  that  in  the  former  the  embryo  has  but  one 
cotyledon,  while  in  the  latter  it  has  two.  When  we  do  not  have 
the  seed,  or  when  it  is  too  small  for  the  determination  of  this 
point  with  ease,  the  classification  may  be  determined  by  the 
following  characteristics  of  the  mature  plant :  The  monocotyle- 
donous plants  usually  have  leaves  with  parallel  veins  and  stems 


EXERCISES  WITH  FLOWERS 


71 


with  irregular  arrangement  of  fibro-vascular  bundles  {endogen- 
ous) ;  the  dicotyledonous  plants  usually  have  leaves  with  net 
veins,  and  stems  with  the  fibro-vascular  bundles  definitely  ar- 
ranged to  form  a  circle  {exogenous). 

Both  groups  are  sub-divided  into  orders,  and  these  orders 
into  families,  these  families  into  genera,  and 
these  genera  into  species.  The  generic  and 
specific  names  constitute  the  scientific  or 
Latin  name  of  the  plant.  The  classification 
and  naming  is  the  same  in  all  civilized 
languages.  The  committing  to  memory  of 
classifications  and  scientific  names  is  wasted 
time  and  useless,  unless  we  understand  the 
relationship  of  plants  and  the  basis  for  their 
groupings.  However,  a  careful  study  of 
plants  will  enable  the  thorough  and  closely 
observing  pupil  to  classify  many  plants  to 
their  families  and  even  to  their  genera  with- 
out the  use  of  a  manual.  Students  who  are 
interested  in  the  classification  of  plants 
should  secure  and  use  a  manual  suited  to  the  locality  in  which 
they  live. 


Fio.  58. — Dandelion 
head.  Composite  type 
of  inflorescence. 


EXERCISES   WITH  FLOWERS 

1.  Plant  Studies. — The  study  should  be  associated  witli  the  plant  as 
a  whole,  provided  time  and  material  will  permit.  The  following  points 
should  be  determined  if  possible: 

(1)  Is  the  plant  monocotyledonous  or  dicotyledonous? 

(2)  Is  it  an  herb,  shrub,  or  tree? 

(3)  Under  what  conditions  did  it  grow? 

(4)  Describe  in  brief  the  root,  stem  and  leaf. 

(5)  Is  the  flower  perfect  or  imperfect? 
Is  the  flower  complete  or  incomplete? 
Is  the  flower  regular  or  irregular? 

Is  the  flower  symmetrical  or  unsymmetrical  ? 


72 


THE  FLOWER 


(6)  If  imperfect,  is  it  monoecious  or  difficious? 

(7)  What  is  the  type  of  inflorescence? 

(8)  Is  the  flower  apetalous  or  complete? 

(9)  Is  the  flower  poly-  or  gamo-sepalous? 

( 10 )  Is  the  flower  poly-  or  gamo-petalous  ? 

(11)  Is  the  ovary  superior  or  inferior? 

( 12 )  How  many  sepals,  petals,  stamens  and  pistils  ? 

(13)  To  what  are  the  different  sets  of  organs  attached?  0 

(14)  If  unsymmetrical,  describe  the  parts. 

(15)  Describe  the  stamens.    How  do  they  open? 

(IC)    Describe  the  pistil  or  pistils.    What  type  of  placenta? 

How  many  ovules   (estimated  by  cross  and  long  sections)  ? 
(17)    If  a  single  pistil,  how  many  carpels  and  cliambers? 

2.  Plant  Description. — Having  determined  the  preceding  points  a  com- 
plete description  of  the  plant  and  flower  should  be  written.  The  pupil  is 
now  ready  to  use  a  manual  for  the  determination  of  the  family,  genus  and 
species.  The  family  characters  should  be  carefully  noted  and  when  an- 
other plant  of  the  same  family  is  studied,  the  pupil  should  try  to  determine 
the  family  without  the  use  of  a  manual. 

3.  Careful  dravi^ings  and  diagrams  should  be  made  of  all  plants  and 
flowers  studied. 


The  following  types  are  suggested  for  these  exercises: 


Monocofyledonous 

Lily 

Tulip 

Lily  of  the  Valley 

Amarillus 

Indian  turnip 

Wheat 

Oats 

Com 


Rose 

Apple  or  pear 

Peach,  plum,  cherry 

Blackberry 

Pea  or  bean 

Bloodroot 

Mustard 

Buttercup 


Dicotyledonous 

Potato  or  tomato 

Sunflower  or  daisy 

Dandelion 

Morning  glory 

Melon  or  gourd 

Maple 

Elm 

Oak 

Willow 


QUESTIONS 


1.  What  are  the  parts  of  the  flower? 

2.  What  constitutes  the  floral  envelope? 

3.  Wliat  constitutes  the  essential  organs? 


QUESTIONS  73 

4.  What   do   you    understand    by    complete,    perfect,    symmetrical    and 
regular  flowers?    Give  examples  of  each. 

5.  What  is  meant  by  apetalous,  gamo-petalous  and  poly-petalous? 

6.  What  is  meant  by  monoecious  and  dioecious"? 

7.  What  is  tiie  difference  between  superior  and  inferior  ovaries?     Give 
examples  of  each. 

8.  Define  carpel,  placenta. 

9.  Give  the  different  forms  of  inflorescence  and  examples  of  each. 


CHAPTER  VI 
REPRODUCTION 

Reproduction  Without  Seed. — We  have  already  referred  to 
some  of  the  methods  of  reproduction  in  plants.  We  have  learned 
that  a  bud  is  an  undeveloped  stem  with  its  undeveloped  leaves ; 
and  that  the  cuttings  of  many  plants  when  placed  in  moist  soil 
or  in  water  will  grow  readily ;  that  is,  the  buds  expand,  a  root 
system  is  developed  and  a  new  plant  possessing  a  complete  set 
of  organs  like  the  parent  is  formed.  In  nature  many  plants,  such 
as  the  willow,  shed  twigs  which  catch  in  the  soil  and  grow.  This 
growing  of  twigs  explains  the  rapidity  with  which  willows  come 
into  existence  along  water  courses.  Many  grasses  and  other 
troublesome  plants  increase  in  number  as  a  result  of  having  the 
underground  stems  torn  in  pieces  by  farming  tools,  thus  per- 
mitting each  bud  to  form  a  new  plant.  We  know  that  this  power 
of  buds  to  grow  makes  it  possible  to  perpetuate  many  valuable 
varieties  by  cuttings,  budding,  and  grafting.  These  methods 
are  the  common  practices  of  florists,  nurserymen,  orchardists 
and  others  who  wish  to  produce  large  numbers  of  plants  of  def- 
inite varieties. 

Many  plants  are  grown  almost  exclusively  from  the  tubers 
or  bulbs  which  we  now  recognize  as  forms  of  stems  (Chapter 
IV),  and  many  of  these  plants  have  partly  or  entirely  lost 
their  power  to  produce  seeds.  Plants  which  have  lost  this 
power  to  produce  seeds  must  be  grown  entirely  from  bulbs,  or 
cuttings,  or  by  budding  or  grafting. 

We  know  that,  although  roots  do  not  generally  produce 
buds,  many  plants  are  propagated  by  shoots  developed  from 
adventitious  buds  formed  on  the  roots.  The  sweet  potato 
74 


THE  TRANSFER  OF  THE  POLLEN  75 

is  a  notable  example  of  a  root  producing  buds  and  young 
plants.  And  linally  we  know  that  even  the  leaves  of  some 
plants  have  the  power  to  produce  buds  which  will  grow  into 
plants.  But  this  is  not  so  strange  as  it  may  first  appear,  when 
we  stop  to  consider  that  the  ovules  which  develop  into  seeds 
are  a  part  of  the  pistil  which  is  a  modified  leaf.  It  is  very 
evident  that  the  preceding  methods  of  reproduction  by  buds 
is  very  rapid  and  that  a  large  number  of  new  individuals  like 
the  parents  can  be  produced  in  a  very  short  time.  It  is  known 
as  the  asexual  or  non-sexual  method. 

By  Flowers  and  Seeds. — However,  the  most  important,  the 
most  complicated,  and  the  highest  method  of  reproduction  is 
by  means  of  seeds  which  are  the  result  of  the  sexual  activ- 
ities of  the  plant.  In  all  the  preceding  methods  of  reproduction, 
each  young  plant  has  but  one  parent.  But  in  reproduction  by 
means  of  seeds  each  plant,  with  a  few  exceptions  (Chapter  V), 
has  two  parents.  The  stamens  may  be  considered  the  male 
organs  and  the  pistils  the  female  organs,  and  the  process  of 
seed  production  may  be  briefly  described  as  follows :  Within  the 
anthers  are  borne  great  numbers  of  pollen  (Fig.  59)  grains 
which  are  readily  recognized  as  the  powder  which  is  so  abun- 
dant in  the  large  lilies  and  many  other  flowers.  This  pollen 
must  be  transferred  to  the  stigma  of  the  pistil  of  the  same  or 
another  flower.  (Fig.  60.)  You  will  recall  that  the  stigma 
is  the  only  part  of  the  plant  that  is  without  an  epidermal  cov- 
ering.    (Page  62.) 

The  transfer  of  the  pollen  is  sometimes  accomplished  by 
some  of  the  many  insect  visitors  that  are  attracted  by  the  honey 
or  odor  of  the  flower,  or  by  humming  birds,  or  in  some  cases 
by  the  wind.  The  transfer  of  the  pollen  is  called  pollination, 
and  should  not  be  confused  with  fertilization.  Each  pollen 
grain  is  a  single  cell  which  undergoes  a  growth  resulting  in  the 
foiTnation   of   a   long,    ddicate   tube  which    grows   downward 


76 


REPRODUCTION 


through  the  style  and  eventually  reaches  the  ovule.  Tlie  tube 
enters  the  ovule  usually  through  the  micropylo  (Chapter  1), 
which  persists  and  is  plainly  visible  in  many  mature  seeds.  In 
the  meantime,  interesting  changes  are  going  on  within  the  small 
ovule,  which  results  in  the  formation  of  a  minute  chamber 
knowai  as  the  embryo  sac.  (Fig.  01  a.)  This  sac  contains 
eight  minute  cells,  one  of  which  is  known  as  the  ovum  or  ccjg. 


Fig.  59. — Types    of    pollen    grain. 


The  tip  of  the  pollen  tube  finally  reaches  this  egg  cell  and  a 
certain  nucleus  from  the  tube  unites  with  the  nucleus  of  the 
egg.  This  is  the  process  of  true  fertilization,  and  this  fer- 
tilized Ggg  now  develops  into  an  embryo  or  young  plant  (Fig. 
01  h)  surrounded  by  a  supply  of  rich  food  for  its  future  nour- 
ishment. This  embryo,  together  with  its  food  supply  and  cover- 
ings, constitutes  the  seed.  (Chapter  V.)  The  parts  involved 
in  this  process  are  so  small  that  it  is  impossible  to  see  them 
without  using  a  compound  microscope,  and  the  study  of  this 
delicate  and  complicated  process  must  necessarily  be  reserved 
for  the  more  advanced  students  of  botany. 

1^0  two  plants  in  nature  are  ever  exactly  alike  and,  there- 
fore, if  the)  pollen  of  one  plant  falls  on  the  pistil  of  a  slightly 


DIFFERENCES  IN  STRUCTURES  OF  SEEDS 


77 


different  plant  of  the  same  or  a  closely  related  species  or  variety, 
the  new  plants  shonld  possess  some  characters  of  both  parents, 
This  gives  a  basis  for  work  in  the  production  of  new  varieties  of 
plants.     (Chapter  XV.) 

Differences  in  Structures  of  Seeds. — There  are  some  facts 
concerning  the  structure  of  the  seed  which 
we  have  already  learned,  but  which  we 
should  now  recall  in  the  light  of  these  new 
facts.  (Chapter  VIL)  The  young  plant 
or  embryo  consists  of  a  very  short. stem  on 
one  end  of  which  is  a  root  tip ;  and  on  the 
other  end  a  plumule,  or  bud,  and  one  or  two 
cotyledons  or  primary  leaves.  It  is  a  com- 
plete plant  possessing  the  three  essential 
parts:  root,  stem,  and  leaf.  We  will  recall 
that  the  seeds  of  corn  and  castor  oil  plants 
contained  embryos  surrounded  by  an  abund- 
ant food  supply  for  their  nourishment  dur- 
ing the  period  of  germination  and  before 
they  had  become  firmly  established  as  inde- 
pendent plants.  We  will  also  recall  that  in 
the  bean  we  found  a  much  larger  embryo 
without  the  surrounding  food  supply.  In  this  case  the  food  for 
the  early  growth  of  the  young  plant  was  in  the  cotyledons. 

The  seeds  of  corn  and  castor  oil  plant  matured  very  early 
when  the  embryos  were  small,  but  with  a  good  supply  of  stored 
food  for  the  growth  of  the  embryo  during  germination.  The 
seed  of  the  bean  matured  much  later,  the  embryo  having  ab- 
sorbed the  surrounding  food  supply  and  stored  it  in  the  coty- 
ledons previous  to  maturity.  In  the  corn,  the  single  cotyledon 
is  an  organ  which  serves  for  the  absorption  of  the  food  supply; 
in  the  castor  oil  plant  the  cotyledons  serve  first  as  organs  of 
absorption  and  later  as  the  primary  leaves;  in  the  bean  they 
serve  for  the  storage  of  the  food  supply  and  as  primary  leaves. 


Fig.  60. — Diagram- 
matic longitudinal  sec- 
tion of  ovary  showing 
developing  ovules. 


78 


REPRODUCTION 


The  examination  of  the  seed  of  a  large  number  of  differ- 
ent kinds  of  plants  will  show  great  variation  in  the  relative 
sizes  of  the  embryos  and  the  amount  of  the  food  supply,  and 
will  suggest  manv  germination  tests  and  growth  experiments. 


Fio.  61. — a,  diagrammatic  drawing  of  stamen  and  pistil  showing  longitudinal  section  of 
ovule.  The  pollen  tube  is  entering  through  the  micropyle;  b,  longitudinal  diasrammatic  sec- 
tion of  ovule  showing  the  formation  of  the  embryo. 


Advantages  of  the  Seed  Method. — It  is  very  evident  that 
sexual  reproduction  is  higher  an  i  more  complicated  than  non- 
sexual reproduction,  but  let  us  see  if  it  is  of  any  advantage.  It 
is  necessarily  much  slower  than  reprod.uction  by  buds,  but  the 


INSECT  POLLINATION  79 

dry  seeds  of  a  plant  can  undoubtedly  resist  greater  extremes 
and  longer  duration  of  heat,  cold  and  drouth  than  buds  and 
can  be  carried  to  much  greater  distances  by  natural  means  and 
by  man.  Many  believe  that  sexual  reproduction  gives  the 
plants  much  more  vigor  than  non-sexual  reproduction.  This 
belief  seems  to  be  supported  by  tlie  fact  that  when  some  varieties 
of  plants  are  grown  continuously  from  cuttings,  tubers  or  bulbs, 
they  tend  to  lose  their  original  varietal  characters  and  vital- 
ity. Sexual  reproduction,  owing  to  the  fact  that  the  two 
parents  are  never  exactly  the  same,  tends  to  cause  variations  in 
plants,  and  results  in  new  varieties.  This  tendency  to  pro- 
duce variations  is  greatly  increased  by  cross  breeding  different 
varieties  and  has  given  rise  to  some  of  our  most  valuable  fruits, 
vegetables  and  oraajnentals.  (Page  148.)  The  transfer  of  the 
pollen  from  the  stamens  to  the  stigma  is  knoAvn  as  pollination 
and  should  not  be  confused  with  fertilization.     (Page  76.). 

Pollen  may  be  carried  by  the  wind,  and  some  of  our  most 
valuable  plants  depend  entirely  upon  the  wind  for  pollination. 
The  corn  and  other  grains  and  grasses  belong  to  this  class.  The 
tassel  of  the  corn  is  a  mass  of  small  staminate  flowers,  while 
each  thread  of  the  silk  represents  a  pistil  with  a  single  grain 
of  corn  for  its  ovary.  During  the  blooming  season  there  is  a 
rain  of  pollen  grains,  some  of  which  fall  upon  the  silk.  Of 
course,  this  is  in  a  sense  very  wasteful  for  the  number  of 
pollen  grains  which  are  lost  is  infinitely  greater  than  the  number 
which  fall  upon  the  silk  {i.  e.,  pistils). 

Insect  Pollination. — The  great  majority  of  our  flowering 
plants  are  pollinated  through  the  agency  of  insects,  which  visit 
the  flower  primarily  to  collect  the  nectar  and  pollen.  Many 
insects  use  the  nectar  immediately  for  food,  but  the  bees  take 
it  into  their  bodies  where  it  undergoes  chemical  changes  by 
which  it  is  transformed  into  honey  and  then  stored  up  for 
future  use.  Many  insects  are  doubtless  attracted  by  the  odors 
of  flowers  and  some  few  may  be  attracted  by  the  color,  although 


80  REPRODUCTION 

we  should  remember  that  it  is  extremely  doubtful  if  insects  cah 
distinguish  shape,  size  or  color  for  any  considerable  distance. 

Interesting  modifications  of  their  parts  are  found  in  many 
flowers.  These  facilitate  pollination  by  means  of  insects,  and 
some  flowers  are  so  specialized  that  certain  insects  are  neces- 
sary for  this  work.  Among  the  simplest  of  these  modifications 
is  the  long  tubular  corolla  of  the  morning  glories  and  honey- 
suckles which  make  it  necessary  that  their  visitors  have  long 
beaks  or  mouth  parts  by  which  they  can  reach  the  nectar  glands 
at  the  bottom.  The  tubular  corolla  of  the  red  clover  is  such 
that  it  is  imperfectly  pollinated  except  by  the  bumble  bee  and, 
therefore,  it  is  practically  impossible  to  grow  red  clover  seed 
without  these  insects.  The  barberry,  and  some  other  plants, 
have  stamens  of  such  character  that  when  touched  by  the  in- 
sect they  serve  as  springs,  striking  the  anthers  against  its  body. 
The  milkweed  and  other  plants  are  so  constructed  that  masses 
of  pollen  may  cling  to  the  body  of  the  insect  and  be  carried 
from  flower  to  flower,  losing  some  pollen  with  each  visit.  Beans, 
peas,  and  similar  flowers  have  peculiarly  shaped  corollas  which 
conceal  the  essential  organs,  but  when  the  insect  settles  upon 
them  these  parts  are  exposed  and  the  lower  surface  of  the  body 
brought  in  direct  contact  with  them.  A  thorough  discussion 
of  the  devices  for  facilitating  the  pollination  by  means  of  insect 
visitors  would  require  a  large  volume  and  then  be  incomplete, 
but  it  is  a  subject  in  which  any  close  observer  can  learn  some- 
thing previously  unknown,  something  not  in  the  books. 

Cross  Pollination. — It  will  be  readily  seen  that  sexual 
pollination  is  usually  accomplished  by  the  pollen  of  one  flower 
on  the  stigma  of  another  flower  of  the  same  or  a  different  plant. 
This  is  known  as  cross  pollitiation  and,  of  course,  results  in 
cross  fertilization  which,  as  previously  stated,  is  believed,  in 
many  cases,  to  give  increased  vigor  to  the  new  generation  of 
plants.  If  this  is  true,  we  are  certainly  justified  in  expecting 
to  find  some  modifications  in  nature  which  prevent  self-pollifir 


DICECIOUS  PLANTS  81 

ation.  If  we  examine  Hewers  carefully  we  will  find  some  in 
whicli  the  stamens  and  pistils  mature  at  different  times  and, 
therefore,  it  is  impossible  for  the  flower  to  be  pollinated  by  its 
own  pollen.  Of  course,  the  flowers  do  not  open  at  the  same 
time  and  pollen  of  some  flowers  will  mature  at  just  the  right 
time  to  be  transferred  to,  and  grown  on,  the  stigma  of  others. 
Sometimes  the  flowers  will  be  pollinated  from  other  flowers  of 
the  same  plant  and  sometimes  by  flowers  of  different  plants. 
In  some  plants  we  can  see  the  effects  of  this  cross  pollination 
in  the  seeds,  as  in  the  case  where  corn  of  one  color  has  been 
pollinated  by  com  of  another,  resulting  in  the  speckled  or  mixed 
ears.  But  in  most  plants  we  do  not  see  the  results  of  cross 
pollination  until  we  grow  the  new  plants.  Cross  pollination  is 
accomplished  in  various  ways.  Some  plants  have  two  kinds  of 
tubular  flowers,  some  with  short  stamens  and  long  pistils,  and 
others  long  stamens  and  short  pistils.  The  insect  visiting  the 
first  flower  gets  pollen  on  the  front  part  of  its  body;  visiting 
the  latter  it  leaves  some  of  the  pollen  on  the  short  pistil  and  gets 
a  load  of  pollen  on  the  back  part  of  its  body.  Therefore,  it  is 
practically  impossible  for  the  flower  to  be  pollinated  with  its 
own  pollen.  Some  plants,  especially  cultivated  varieties,  have 
impotent  pollen  and,  therefore,  cannot  be  pollinated  with  their 
own  pollen  or  with  pollen  from  plants  of  the  same  variety. 
Many  apple,  pear  and  plum  growers  mix  their  varietiesi  in  the 
orchard  so  as  to  insure  pollination  and  thus  get  the  stimulating 
effect  of  fertilization  and  secure  a  richer  harvest.  In  some  cases, 
growers  may  even  set  a  few  trees  of  an  inferior  variety  in  order 
to  secure  satisfactory  cross  pollination  of  the  desirable  varieties. 
In  some  plants,  such  as  the  common  banana,  the  pollen  is  useless 
and  the  plants  no  longer  produce  seeds. 

Dioecious  plants  (Chapter  V)  are  necessarily  cross  pollin- 
ated, and  many  savage  and  half-civilized  races  learned,  many 
centuries  ago,  the  necessity  of  growing  the  staminate  as  well 
6 


82  REPRODUCTION 

as  the  pistillate  trees,  although  they  had  no  explanation  for  this 
phenomenon  of  nature. 

Self-Pollination, — However,  the  flowers  of  some  plants  are 
very  generally  self-pollinated.  Wheat  belongs  to  this  group  or 
class. 

Buds  That  Never  Open. — The  buds  of  some  flowers  never 
open,  making  cross  pollination  impossible.  Such  flowers  are 
called  cleistogamous.  Some  species  of  violets  produce  incon- 
spicuous cleistogamous  buds  under  the  leaf -mold,  these  buds  pro- 
ducing abundant  seeds,  while  the  showy^  flowers  of  these  species 
are  usually  sterile. 

EXERCISES    IN    POLLINATION 

1.  Carriers  of  Pollen. — Observe  flowers  and  note  the  insects  which 
visit  them.  Are  the  different  species  of  flowers  visited  by  the  same  species 
of  insects?     Do  the  insects  exercise  a  choice  in  visiting  flowers? 

2.  Examine  pollen  of  a  number  of  flowers  under  the  microscope.  Make 
drawings. 

.3.  Pollen  Grovi^th  in  Sugar  Solution.— ^lake  a  solution  by  boiling 
one  part  of  sugar  in,  ten  of  water.  Put  a  spoonful  into  each  of  several 
watch  glasses.  Mix  the  pollen  of  several  flowers  into  them  and  keep  cov- 
ered. Examine  a  drop  of  the  fluid  with  pollen  under  the  miscroscope  from 
time  to  time  and  note  the  germination. 

QUESTIONS 

1.  How*  do  you  account  for  the  rapid  increase  in  numbers  of  willows 
and  similar  plants  along  water  courses? 

2.  Can  other  plants  be  produced  in  a  similar  manner? 

3.  How  do  w^e  make!  use  of  this  power  of  reproduction  in  the  grow- 
ing plant? 

4.  How  are  many  grasses  and  other  pests  frequently  propagated? 

5.  Give  a  list  of  plants  that  grow  from  bulbs. 

6.  Give  a  list  of  plants  that  grow  from  tubers. 

7.  Give  a  list  of  plants  that  are  seldom  or  never  grown  from  seeds. 
How  are  they  grown  ? 

8.  Do  roots  produce  buda?    Give  some  exceptions. 

9.  Explain  pollination. 

10.  Explain  fertilization. 

11.  Explain  cross  pollination. 

12.  Explain  self-pollination. 

13.  Explain  cleistogamous  seed  production. 


CHAPTER  VII 

FRUITS   AND   SEEDS 

We  make  use  of  plants  in  a  great  many  ways,  but  tlie  most 
important  way  is  as  food  for  the  sustenance  of  life  of  man 
and  beast.  Among  the  most  important  parts  of  the  plants  used 
for  this  purpose  are  the  seeds  and  fruits.  However,  these  terms 
{fruit  and  seed)  are  very  indefinite  and  should  be  used  with 
care.  Fruits  and  vegetables  are  frequently  confused;  the  to- 
mato is  usually  spoken  of  as  a  vegetable,  although  the  edible 
part  does  not  differ  materially  from  many  true  berry  fruits. 
Botanically,  a  fruit  is  the  ripened  ovary,  or  the  ripened  ovary 
ivith  such  other  parts  as  may  he  united  to  it.  However,  some 
fruits,  such  as  the  banana  and  the  navel  orange,  have  lost  the 
power  to  produce  seeds  and  the  fruit  consists  of  only  the  ovary. 
They  are  known  as  seedless  fruits,  and  these  plants  must  be 
propagated  by  some  of  the  non-sexual  methods  previously  re- 
ferred to.  (Chapter  VI.)  Although  we  usually  think  of  fruits 
as  being  fleshy  structures,  the  cotton  boll,  a  gourd,  a  pepper 
pod,  or  a  bean  pod  are  fruits  as  truly  as  is  the  peach  or  apple. 
The  seed  is  the  mature  ovule  with  its  enclosed  embryo,  or  as  wo 
may  have  learned,  the  embryo  ivith  food  supply  and  coverings. 
The  final  result  of  plant  energy  is  the  production  of  its  kind 
and  the  distributing  of  its  offsprings  as  far  as  possible.  Each 
species  of  plant,  if  uncontrolled  by  climate,  water,  soil,  animals 
and  other  plants  would  eventually  tend  to  occupy  the  entire 
earth.  But  many  plants  cannot  spread  beyond  a  certain  limit, 
because  of  the  extremes  of  the  climate;  others  are  checked  for 
want  of  suitable  soil ;  others  by  bodies  of  water  or  desert  plains ; 
and  still  others  by  c(miing  into  competition  with  other  plants 
which  are  stronger  and  crowd  them  out.     Man  has  taken  advan- 

83 


84 


FRUITS  AND  SEEDS 


tagc  of  this  tendency  of  plants  to  reproduce  themselves  and  to 
vary  their  characters,  and  has  selected  those  which  are  the  best 
suited  to  his  purposes,  and  has  protected  and  cultivated  them. 
By  his  intelligent  management  he  has  increased  their  value  to 
himself.     (Chapter  XV.) 

For  convenience  we  will  classify  fruits  as  follows : 


Fleshy. 


Dry. 


Drupe . . . . 
Pome 
Berry 
Accessory 

Dehiscent . 


Indehiscent. 


f  Simple   drupe 
Aggregate 
Multiple 


I    Pod  or  capsule 
I   Leffiinie 


f  Achens 
I    C'aryopsisi 
I    Samara  or  key 
Nut 


The  drupe  or  stone  fruit  has  the  seed  surrounded  by  a 
strong,  or  hard,  stony  growth  (endocarp)  which  is,  in  turn, 
surrounded  by  a  fleshy  growth  (exocarp).  The  stony  and 
fleshy  growths  constitute  the  ovary.  The  peach  (Fig.  ()2), 
plum  and  cherry  are  of  this  type,  and  each  fiiiit  is  a 
single  or  simple  ovary  derivoKl  from  a  single  flower.  (Page  55.) 
There  are  several  modifications  of  the  simple  drupe  which 
are  given  special  names,  but  the  differences  are  superficial. 
They  are: 

(a)  The  aggregate  fruit  which  consists  of  a  number  of 
ripened,  fleshy  pistils  derived  from  a  single  flower.  The  black- 
berry and  raspberry  are  excellent  types. 

(h)  The  multiple  fruit  which  consists  of  a  number  of  small 
single  pistils  each  derived  from  a  single  flower.  The  mulberry 
is  a  type.     Although  the  blackberry  and  mulberry  fruits  show 


THE  POME 


85 


a  very  striking  superficial  resemblance,  they  are  radically  differ- 
ent; the  former  representing  a  single,  rather  large  flower 
with  many  pistils,  and  the  latter  a  number  of  very  small  flowers, 
each  having  a  single  pistil.  None  of  the  above  are  true  berries 
from  the  botanical  viewpoint,  but  the  name  is  so  closely  asso- 


riie  peach,  the  drupe  type  of  iiuit. 


ciated  with  them  that  it  is  practically  impossible  to  make  a 
change. 

The  pome  is  a  fruit  in  which  the  ovary,  or  ot^aries,  the 
calyx  and  receptacle  are  united,  both  becoming  fleshy.  The  tips 
of  the  sepals  persist  at  the  blossom  end  of  the  fruit  and  the 


86 


FRUITS  AND  SEEDS 


enclocarp  develops  as  a  papery  core.     The  apple  (Fig.  03),  pear 
and  qiiiiico  are  typical  of  this  group. 

The  true  berry  is  a  more  or  less  leathery  structure  enclosing 
a  mass  of  seeds.  It  may  consist  of  the  ovary  only,  or  of  the 
ovary  enclosed  in  the  cal^'x.  Many  plants  belonging  to  a  great 
diversity  of  families  produce  fruits  of  this  type.     Among  the 


Fio.  63. — The  apple,  the  pome  type  of  fruit. 

most  important  are  the  gooseberry,  huckleberry,  cranberry, 
grape,  orange,  melon  and  cucumber.  However,  melons,  cucum- 
bers and  gourds  and  other  fruits  belonging  to  the  family  Cucur- 
hitacecp  are  frequently  given  a  special  name  of  "  pepo." 

The  accessory  fruit  is  the  fleshy  receptacle  of  a  single  flower 
covered  wuth  achenes  which  are  usually  called  seeds ;  the  straw- 
berry belongs  to  this  t)'pe. 

The  dry  fruits  are  those  in  which  the  ovaries  develop  into 
dry  pods.    If  this  pod  opens  and  releases  the  seeds  it  is  dehiscent 


THE  NUT  87 

(Fig.  64,  a),  but  if  it  does  not  open  until  burst  by  the  germi- 
nating seed,  it  is  indeliiscent.     (Fig.  64,  b.) 

The  term  pod  or  capsule  will  apply  to  any  of  the  dehiscent 
fruits,  regardless  of  the  number  of  caiiDels  involved  in  its 
formation.  The  term  legume  applies  to  those  peculiar  elongated 
pods  (Fig.  64,  a)  of  the  legwriinoseoe  or  pea  family,  each  of 
which  represents  a  single  capsule  of  two  valves  and  a  single 
placenta3. 

The  indehiscent  fruits  are : 

(a)  The  achene,  a  small,  dry,  one-seeded  pod  representing 
one  or  more  carpels.     (Fig.  64,  b.) 


Fig.  64. — ^a,  legume  or  dehiscent  pod ;  b,  an  achene  or  indehiscent  pod  cut  so  as  to  show  the 
enclosed  seed;  c,  caryopsis  or  grain  showing  the  pericarp  or  ovary,  the  integument  or  seed 
coat,    the  aleurone  cells  and  the  starch  area;  d,  samara  or  key  fruit;  e,  acorn  or  nut  type. 

(b)  The  caryopsis  or  grain  in  which  the  pod  or  ovary  is 
united  to  the  seed.     (Fig.  64,  c.) 

(c)  The  samara  or  key  in  which  the  pod  is  developed  into 
a  thin  flat  wing.     (Fig.  04,  d.) 

(d)  The  nut  is  a  single  seed  in  which  the  ovary  is  developed 
into  a  hard,  bone-like  or  horn-like  covering. 

There  are  several  types  of  nuts,  such  as  the  acorn  (Fig.  64,  e) 
which  is  a  cup  formed  of  involucral  leaves ;  the  hazelnut,  chest- 
nut, and  beechnut,  in  which  the  nuts  are  enclosed  in  a  pod  also 
formed  of  involucral  leaves ;  the  hichory  nut  inclosed  in  a  shuck, 
probably  composed  partly  of  calyx  and  partly  of  involucral 
loaves,  which  tend  to  split  when  dry.  The  ivalnut  is  of  the  same 
type  as  the  hickory  nut,  but  does  not  tend  to  split;  it  is  some- 


88  FRUITS  AND  SEEDS 

what  fleshy  and  resembles  the  drupes,  ])iit  the  fleshy  part  is  of 
an  entirely  diflerent  origin  from  that  of  the  trne  drupes, 

F^g  Type. — There  are  some  fruits  which  are  diflicult  to 
classify  in  any  of  the  preceding  groups  and  must  be  distin- 
guished by  special  names.  Among  the  most  important  is  the 
synconium  or  fig  fruit  which  is  derived  from  an  enlarged,  soft, 
hollow  stem  enclosing  a  hirge  number  of  very  small  flowers 
which  are  never  exposed.  Many  people  believe  the  fig  produces 
fruit  without  blooming,  but  this  is  not  true. 

Seed  Distribution. — If  seeds  are  to  fulfill  their  place  in 
nature  they  must  be  distributed  over  a  considerable  range  of 
country.  If  they  are  all  dropped  within  the  immediate  vicin- 
ity of  the  parent  plant,  the  new  plants  will  be  too  crowded,  the 
weaker  cannot  survive,  and  the  vigor  of  both  parent  and  off- 
spring will  be  impaired.  Seeds  are  mostly  carried  by  wind 
and  water,  by  animals  and  by  man.  It  is  very  evident  to  the 
most  casual  observer  that  of  the  enormous  quantities  of  seeds 
produced  by  a  single  plant,  very  few  can  ever  serve  their  primary 
purpose  in  nature,  that  of  producing  new  plants.  The  majority 
will  be  eaten  by  animals,  or  will  fall  in  unfavorable  places  where 
they  cannot  germinate,  while  many  of  those  that  do  germinate 
will  never  grow  to  maturity.     (Fig.  (55.) 

Carried  by  Water. — It  is  very  easy  to  understand  how  seeds 
can  be  carried  from  place  to  place  by  water.  Those  that  are 
buoyant  will  be  carried  along  by  streams,  or  float  over  the 
surfaces  of  lakes.  Those  that  will  not  float  may  be  carried  along 
in  the  mud  and  debris.  Heavy  rainfall  will  carry  many  seeds 
for  considerable  distances  and  will  frequently  cover  them  with 
earth.  Seeds  that  float  are  frequently  propelled  by  wind  and 
carried  for  long  distances  over  lakes  and  other  large  bodies  of 
water.  Seeds  from  plants  growing  near  the  salt  water  will 
frequently  be  carried  for  long  distances  by  means  of  water  and 
wind  and  find  a  resting  place  on  other  shores.     Of  course,  it  is 


RESISTANCE  TO  HEAT,  COLD  AND  DRYNESS  89 

importaut  that  seeds,  wliicli  are  carried  in  tliis  manner,  shall 
be  of  such  character  as  not  to  be  easily  injured  by  long  sub- 
mergence in  water,  and  this  is  especially  true  of  those  seeds 
which  are  carried  by  salt  water.  The  cocoanut  is  a  striking 
example  of  a  large  floating  seed  which  frequently  is  carried 
on  the  salt  water.     The  vegetation  of  the  volcanic  and  coral 


Fig.  65. — Devices  for  seed  distribution. 

islands  of  the  sea  frequently  owes  its  origin  to  seeds  of  this 
type. 

Resistance  to  Heat,  Cold  and  Dryness. — The  seeds  of  many 
plants  are  also,  resistant  to  exti'cme  drying  and  to  extreme  heat 
and  cold.  The  seeds  of  some  plants  will  lie  in  the  soil  for 
years  waiting  nntil  the  conditions  are  favorable  for  their  germin- 
ation, while  the  seeds  of  other  plants  will  perish  in  a  few 
weeks  or  months,  even  when  kept  under  the  most  favorable 
conditions. 


90  FRUITS  AND  SEEDS 

Carried  by  Wind. — We  have  all  observed  the  dispersal  of 
seeds  by  means  of  the  wind.  Of  course,  strong  air  currents 
will  carry  light  seeds  for  great  distances,  but  many  seeds  have 
special  structures  which  are  very  important  in  this  work.  The 
maple,  ash  and  elm  have  membranous  wings,  or  outgrowths  by 
which  the  wind  carries  them.  These  outgrowths  are  a  part 
of  the  ovary.  The  dandelion,  lettuce,  thistle  and  many  other 
plants  have  seeds  which  are  enclosed  in  the  ovary  {achenes), 
on  which  is  developed  a  downy  outgrowth  serving  as  an  air 
float,  a  sort  of  balloon  or  parachute.  The  seeds  of  the  milkweed 
bear  a  superficial  resemblance  to  those  of  the  dandelion,  but  are 
quite  different.  You  will  recall  that  the  dandelion  is  an  inde- 
hiscent  fruit,  w^hile  the  milkweed  is  dehiscent.  The  outgrowth 
on  the  former  is  from  the  ovary ;  on  the  latter  from  the  seed 
coat.  Some  plants,  especially  weeds,  of  which  the  tumble  w^eed  is 
the  most  striking  example,  will  break  loose  and  be  carried  by  the 
Avind  for  great  distances,  distributing  their  seeds  as  they  travel. 

Carried  by  Man  and  Animals. — The  lower  animals  are  the 
involuntary  carriers  of  many  seeds,  and  man,  the  highest  of 
the  animals,  is  both  an  involuntary  and  a  voluntary  carrier. 
The  seeds  of  many  fruits  will  pass  through  the  alimentary  canal 
of  animals  unharmed  and  will  grow  if  dropped  in  suitable 
places.  Squirrels  and  other  animals  bury  nuts  and  other  seeds 
w^iich  grow ;  while  birds  accidentally  drop  the  seeds  of  cherries, 
berries  and  other  fruits,  here  and  there.  Burs  and  many  other 
seeds  have  spines  or  hooks  by  which  they  cling  to  animals.  Man 
carries  many  seeds  in  feed  and  bedding  for  himself  and  live 
stock,  in  packing  materials,  and  in  grain  for  various  agricultural 
and  commercial  purposes.  The  shipping  of  grain  and  grass 
seeds  from  country  to  country  has  been  the  means  of  introduc- 
ing many  of  our  most  troublesome  weeds. 

Seeds  Thrown. — IMany  plants  have  peculiar  devices  by 
which  seeds  are  thrown  for  considerable  distances.     The  touch- 


EXERCISES  CONCERNING  FRUITS  AND  SEEDS  91 

me-iiot  is  an  excellent  illustration  of  this  last  method.  The  pod 
splits  suddenly  and  the  parts  curl  with  such  force  as  to  throw 
the  seeds  out. 


EXERCISES  CONCERNING  FRUITS  AND  SEEDS 

1-  The  Peach, — Examine  the  fruit  of  the  peach.  Wliat  part  of  the 
flower  is  involved  in  its  make-up?  How  many  carpels  does  it  represent? 
Note  the  fleshy  exocarp,  the  hard  endocarp  and  the  seed. 

2.  Blackberry. — Examine  the  fruits  of  the  blackberry  or  dewberry. 
What  part  of  the  flower?  How  many  carpels?  Where  are  the  exo-  and 
endocarps  ? 

3.  Compare  the  fruits  and  tell  how  the  blackberry  diff"ers  from  the 
raspberry. 

4.  Compare  the  fruits  and  state  liow  the  strawberry  differs  from  the 
blackberry. 

5.  Compare  the  fruits  and  state  how  the  mulberry  differs  from  the 
blackberry. 

C.  Apple. — Examine  the  fruit  of  the  apple  or  pear.  What  parts  of 
the  flower  are  involved  in  its  make-up?  How  many  pistils  and  carpels 
does  it  represent?     How  does  the  endocarp  differ  from  that  of  the  peach? 

7.  Gooseberry. — Examine  the  fruit  of  the  gooseberry.  What  parts 
of  the  flower  ai-e  involved  in  its  make-up?  How  many  pistils  and  carpels? 
What  is  the  dry  part  on  the  tip? 

8.  Melon,  Orange  and  Tomato.  —  Cut  a  melon  or  cucumber,  an 
orange  and  a  tomato  in  cross-section.  Study  in  the  same  manner  as  the 
gooseberry. 

9.  Seedless  Fruits. — Cut  a  navel  orange  and  a  luaiiana  in  cross-sec- 
tion and  study  in  tlie  same  manner.     How  do  they  difi'er? 

10.  True  Pods. — Examine  the  pod  of  a  bean  or  pea  or  similar  dry 
fruit.  How  many  pistils?  How  many  carpels?  Where  are  the  seeds 
attached  ? 

11.  Examine  as  many  other  forms  of  pods  as  possil)le  and  answer 
the  same  questions. 

12.  Winged  Fruits. — Study  the  seeils  of  tlic  maple,  dandidion,  etc., 
for  methods  of  distribution. 

1.'5.  Study  the  seeds  of  Uie  milkweed  and  compare  with  tli(>  dande- 
lion. 

14.  Burs. — Study  burs,  stick-tigiits  and  other  seeds  for  special  devices 
for  distribution. 


92  FRUITS  AND  SEEDS 

15.  Explosive  pods  such  as  the  touch-me-not  and  witch  luizcl  slioulcl 
be  collected.     Note  their  explosive  power. 

10.  Examine  bladdery  seeds  and  ovaries  of  such  plants  as  may  be 
available. 

QUESTIONS 

1.  What  is  a  fruit? 

2.  What  is  a  seed? 

3.  Give  the  different  types  of  fruits. 

4.  Define  each. 

5.  Give  examples  of  each. 

6.  Give  difi'erent  methods  of  seed  distribution   and  examples  of   each. 


CHAPTER  VIII 
ANATOMY  OF  STEMS,  ROOTS,  AND  LEAVES 

We  have  learned  that  stems  are  composed  of  strands  of 
woody,  fibrous  material  embedded  in  a  softer  substance  or  pith, 
and  that  this  entire  structure  is  enclosed  in  a  water-proof  sheath 
of  epidermis  or  bark.  We  have  also  learned  that  the  arrange- 
ment of  these  strands  of  fibrous  material,  which  are  known  as 
fibro-vascular  bundles,  is  different  in  the  monocotyledonous  and 
dicotyledonous  stems.  In  the  former  (Fig.  66)  they  are  dis- 
tributed throughout  the  stem  except  in  those  plants  in  which 
the  stem  is  hollow,  while  in  the  latter  they  are  arranged  in  a 
circle.  (Fig.  67.)  This  difference  in  the  arrangement  of  the 
mono-  and  dicotyledonous  stems  enables  us  readily  to  recognize 
these  two  groups  of  plants.     (Chapter  III.) 

Cellular  Structure. — If  we  can  examine  cross  and  longitud- 
inal sections  of  a  monocotyledonous  stem  with  a  microscope,  we 
will  find  that  the  pithy  part  of  the  stem  is  composed  of  large, 
thin-walled  cells.  (Fig,  68.)  We  have  previously  referred  to 
cells,  but  have  not  given  an  explanation  of  them.  All  parts  of  all 
plants  are  made  up  of  cells  of  which  this  is  the  simplest  type. 
The  cell  is  the  unit  of  the  plant  structure,  the  same  as  a  brick 
or  a  stone  may  be  the  unit  of  a  building.  The  name  ''  cell  " 
was  given  by  the  students  of  botany,  soon  after  the  invention 
of  the  microscope,  who  saw  the  plant  as  a  structure  composed 
of  many  minute,  apparently  empty  boxes  or  cells.  Later 
students  learned  that  these  cells  when  young  and  active  con- 
tained a  substance  which  we  now  call  protoplasm  (Fig,  69), 
and  still  later  students  learned  tliat  protoplasm  might  exist  with- 
out being  enclosed  in  a  cell-wall.     Therefore,  the  definition  of 

93 


94 


ANATOMY  OF   STEMS,  ROOTS,  AND  LEAVES 


a  cell  was  protoplasm  which  may  he  either  naked  or  enclosed  in 
a  cell-wall,  or  a  small  microscopic  chamher  from  which  the 
protoplasm  has  been  withdrawal. 

The  protoplasm  is  an  albuminous  substance  more  nearly  like 
the  white  of  an  egg  than  any  other  substance  with  which  we  can 
compare  it.  It  is  that  part  of  the  plant  in  which  the  life  is 
said  to  exist,  and,  so  far  as  we  know,  is  not  different  from  the 
protoplasm  of  the  animal  cell.     In  its  active  condition,  it  is 


66. — Cross-section  of  monocotyledonous  stem  showing  arrangement  of  the   fibro- 
vascular  bundles. 
Fig.   67. — Cross-section  of  dicotyledonous  stem  showing  arrangement  of  fibro-vascular 
bundle. 
Fig.  68. — Parenchyma  cells. 


very  sensitive  to  change  of  humidity,  temperature,  and  to  poison- 
ous substances.  The  active  growing  cells  of  the  plant  are  rich 
in  protoplasm,  but  many  cells  which  persist  throughout  the 
entire  life  of  the  plant  die  and  lose  their  protoplasm.  In  fact, 
the  great  bulk  of  the  cells  of  most  of  our  higher  plants  is  dead. 
The  cell  can  be  studied  to  the  best  advantage  in  some  of  the 
water  plants,  especially  the  algae,  which  will  be  studied  later. 
If  we  examine  a  very  small  amount  of  one  of  these  plants  known 
as  Spirogyra  under  the  microscope,  we  find  that  it  is  made 
up  of  a  single  row  of  elongated  cells  placed  end  to  end.  These 
cells  appear  to  be  rectangular,  but  they  are  cylindrical  tubes 
closed  at  both  ends.  We  very  readily  recognize  the  cell-wall  and 
the  chlorophyll,  which  is  in  a  body  known  as  the  chromatophore. 


CELLULAR  STRUCTURE 


95 


If  we  examine  the  cells  of  other  plants,  we  find  that  these  chrom- 
atophores  vary  greatly  in  size  and  shape.  The  other  parts  of 
the  cell  are  not  so  easily  recognized.  But  if  we  will  keep  some  of 
the  algae  in  alcohol  for  a  few  hours  the  chlorophyll  will  be  partly 
or  entirely  removed  so  that  we  can  recognize  the  very  delicate 
layer  of  protoplasm  lying  next  to  the  cell- 
wall  and  also  delicate  strands  extending 
across  the  cell.  This  will  be  greatly 
aided  by  treating  the  algse  with  eosin  or 
some  other  coloring  matter  which  will 
stain  the  protoplasm.  In  this  plant,  the 
protoplasm  does  not  completely  fill  the 
cell,  but  there  are  large  spaces  which  are 
filled  with  water  or  air  and  known  as 
vacuoles.  We  will  also  be  able  to  recog- 
nize the  nucleus  which  is  a  very  import- 
ant part  of  the  cell. 

The  nucleus  is  protoplasmic  in  char- 
acter and  very  complicated  in  structure. 
It  is  present  in  nearly  all  living  cells,  and 
when  the  cell  divides  the  nucleus  also  divides,  one  part  going 
into  each  new^  cell.  In  a  few  plants,  the  cells  are  multinuclear, 
and  when  they  divide  some  nuclei  are  found  in  each  new  cell. 

Cells  also  contain  many  compounds.  The  most  prominent 
is  the  starch,  which  can  be  readily  recognized  by  examining 
a  very  thin  section  of  potato  or  apple  under  the  microscope. 
If  we  treat  this  section  with  iodine,  the  starch  grain. will  turn 
blue.  The  starch  grains  of  different  plants  differ  in  size  and 
form ;  this  fact  enables  the  microscopist  to  decide  on  amount 
and  character  of  many  adulterations  of  foods  and  drugs.  The 
cells  also  contain  sugar,  fats,  oils  and  other  compounds  which 
will  be  discussed  later.     (Chapter  IX.) 

As  the  plant  grows  the  cells  undergo  many  changes  and  modi- 
fications.    These  variations  are  much  more  pronounced  in  the 


Fig.  G9. — A  typical  plant 
cell  showing  protoplasm. 


96 


ANATOMY  OF  STEMS,  ROOTS,  AND  LEAVES 


higher  or  flowering  plants  than  in  the  lower  forms.  Some  cells 
have  thin  walls  and  contain  a  great  deal  of  food  materials  which 
make  them  valuable  foods  for  man  and  other  animals.  Some 
are  fibrous  in  character  and  have  thick  walls  which  make  them 


Fig.  70. — Cross-section  of  fibro-vascular  bundle  from  corn  stem, 


Liscussion 


of 


useful  in  many  industries.     We  will  give  a  brief  d 
these  different  types  of  cells. 

Parenchyma. — The  cells  of  pith  are  large,  somewhat  vari- 
able in  size,  thin-walled,  more  or  less  spherical  in  shape  and 
usually  show  irregular  spaces  between  them.  They  are  known 
as  parenchyma  or  soft  cells.     (Fig.  OS.) 

The  great  majority  of  the  cells  of  fruits,  grains  and  other 
edible  parts  of  plants  are  made  up  of  parench\Tua  cells.     Their 


EACH  FIBRO-VASCULAR  BUNDLE  97 

value  as  food  depends  on  the  size  of  the  cells,  the  thinness  of 
the  cell-walls,  the  amount  and  digestible  character  of  the  food 
(carbohydrates,  hydrocarbons,  proteids ;  Chapter  IX)  which 
they  contain,  and  the  absence  of  poisonous  or  injurious 
compounds. 

Each  fibro-vascular  bundle  is  made  up  of  a  variety  of  cells. 
In  the  young  bundle  of  the  monocotyledonous  stem  (Fig.  70) 
is  a  small  group  of  cells  known  as  the  cambium.    They  have  the 


mmm 


Fig.  71. — Tracheary    tissue. 

power  of  rapid  growth  and  division  and  are  primarily  respon- 
sible for  the  increase  in  diameter  of  the  monocotyledon  stem. 
After  a  comparatively  short  time  they  lose  the  power  of  division 
and  this  checks  the  increase  in  diameter  of  the  stem.  On  one 
side  of  the  bundle  will  be  a  mixture  of  large  and  small  cells 
constituting  the  woody  part.  Some  of  these  cells  have  peculiar 
thickenings  of  the  cell-walls  forming  rings,  spirals,  pits,  etc. 
They  are  known  as  tracheids  and  tracheary  cells.  (Fig.  71.) 
On  the  opposite  side  of  the  bundle  is  a  group  of  small,  thick- 
vralled  cells  constituting  the  fibre  or  bast.  (Fig.  72.)  There 
are  other  types  of  cells  which  will  be  described  later.  A  mono- 
cotyledonous stem  increases  in  diameter  for  a  limited  time  only, 
partly  by  the  increase  in  the  size  of  the  fibro-vascular  bundles 
7 


98  ANATOMY  OF  STEMS,  ROOTS,  AND  LEAVES 

and  partly  by  the  increase  in  number  of  bundles.  The  hard 
outer  covering  of  the  corn  and  similar  plants  is  composed  of 
these  fibro-vascular  bundles. 

The  dicotyledonous  stem  has  bundles  made  up  of  the  same 
kind  of  cells  which  are  arranged  very  diti'erently.  The  outer 
part  of  the  bundle  contains  the  bast ;  the  inner,  the  woody  cells ; 
and  between  the  two  groups  lies  the  cambium  which  persists 
throughout  the  entire  life  of  the  plant.     The  cells  of  the  cam- 


FiQ.  72. — Fibrous  tissue;  bast  and  wood  cells. 

bium  form  a  continuous  layer  of  living,  growing  cells.  These 
cells  divide  repeatedly  cutting  off  innei*  layers  which  go  to  form 
layers  of  wood  and  outer  layers  which  eventually  help  to  form 
the  outer  parts  of  the  stem.  All  the  other  types  of  cells  are 
derived  from  these  cambium  cells.  Among  the  bast  cells  are 
the  peculiar  sieve  cells  (Fig.  73)  or  tubes,  so  called  because  of 
the  peculiarly  perforated  cross  walls.  On  the  opposite  side  of 
the  cambium  are  a  number  of  cells  and  tubes  which  have  peculiar 
thickenings  on  the  inside  of  the  walls.  If  the  cells  are  short, 
more  or  less  tapering  at  the  ends  and  with  numerous  pits  in  the 
walls,  they  are  known  as  traclieids,  but  if  they  are  elongated  into 
tubes  in  which  the  wall  thickenings  take  the  form  of  spirals, 
rings,  pits,  etc.,  they  are  known  as  tracheary  tissue.  (Fig.  71.) 
This  term  is  also  used  to  include  the  tracheids.  This  tracheary 
tissue  is  surrounded  by  long  fihrous  or  irood  cells.  (Fig.  72.) 
The  outer  part  of  the  bundle  containing  the  sieve  and  bast  cells 
is  called  the  phloem  region ;  the  inner  part  containing  the  trach- 
eary and  wood  fibre  is  called  the  Tylem  region. 


THE  DICOTYLEDONOUS  STEM 


99 


111  the  centre  of  the  stem  is  the  pithy  stele  composed  of 
parenchyma  cells.  The  libro-vascular  bundles  are  also  separated 
by  masses  of  thin-walled  cells  called  the  medullary  rays  (Fig. 
74),  and  the  entire  structure  is  enclosed  in  an  epidermal  mass 
of  cells  known  as  the  bark.  In  soft  stems  of  the  herbaceous 
plants,  geranium,  etc.,  the  bundles  are  separated  by  thick  medul- 
lary rays  while  in  hard,  woody  stems  of  the  tree,  the  rays  are 
very  thin.    In  the  stems  or  trunks  of  young  trees,  the  bundles  are 


Fig.  73. — Sieve   tissue. 
'4. — Cross  section  of  dicotyledonous  woody  stem,  showing  annular  rings,  medullary 
rays  and  bark. 


few  and  the  rays  thick,  but  the  number  of  bundles  increases  and 
the  rays  become  thinner  and  thinner  with  age.  If  we  cut  across 
a  large  stem,  i.e.,  the  trunk  of  a  tree,  we  can  readily  recognize 
the  small  point  in  the  centre  which  we  call  the  pith  or  stele, 
the  colored  heart-wood,  the  sap-wood,  and  the  bark.  We  will 
also  note  the  great  number  of  circles  known  as  the  annular 
rings.  (Fig.  74.)  In  many  trees,  each  ring  represents  one 
year's  growth.  We  will  also  observe  a  large  number  of  lines 
which  radiate  from  the  centre  and  are  known  as  medullary  rays. 
(Fig.  74.)     In  young  stems  these  rays  are  composed  of  pareii- 


100  ANATOMY  OF   STEMS,  ROOTS,  AND  LEAVES 

cbjma  cells  aud  are  a  coutiiiuation  of  the  pith  cells ;  but  in  older 
stems  they  are  frequently  compressed  into  extremely  thin,  flat 
layers  of  cells  separating  the  fibro-vascular  bundles. 

The  bundles  increase  in  mnnber  with  the  age  of  the  plant. 
In  young  stems  the  bark  is  soft  and  greenish  in  color  and  can 
be  readily  separated  from  the  underlying  woody  parts.  In  the 
older  stems  the  outer  bark  is  dead  and  frequently  cracked  and 
conceals  the  soft  or  true  bark.  In  peeling  the  stem  the  separa- 
tion sometimes  occurs  in  the  cambium.  The  increase  in  the 
number  of  cells  in  the  dicotyledonous  stems  is  confined  almost 
entirely  to  the  cambium  layer  of  cells  which  produces  new  cells 
for  both  the  xylem  and  the  phloem.  Therefore,  it  will  be  readily 
seen  that  the  formation  of  the  new  layers  of  xylem  cells  results 
in  increasing  the  diameter  of  the  stem  without  increasing  the 
inner  diameter  of  the  cylinder  of  bark.  This  increase  of  the  size 
of  the  stem  must  necessarily  exert  a  considerable  strain  on  the 
bark  covering,  which  results  in  the  very  slow  splitting  and  peel- 
ing of  the  outer  bark.  This  explains  the  roughness  of  the  bark 
of  most  of  our  trees  and  the  characteristic  natural  peeling  of 
many  others.  As  the  old,  outer  bark  is  gradually  shed,  the 
newly  formed  inner  bark  becomes  the  outer  and  new  layers 
are  formed  from  below. 

Cause  of  Annular  Rings. — Tke  formation  of  the  cells  of  the 
xylem  is  not  uniform  throughout  the  season.  In  our  northern 
climate,  the  cells  formed  in  the  first  part  of  the  growing  season 
are  larger  and  have  thinner  walls  than  those  formed  later.  This 
difference  causes  the  so-called  annular  rings. 

Sap-Wood.- — The  light-colored  sap-wood  is  composed  of  cells 
in  which  there  is  little  or  no  growth,  but  which  contain  more 
or  less  protoplasm. 

Heart-Wood. — The  dark-colored  heart-wood  is  composed  of 
cells  from  which  the  protoplasm  has  disappeared.     They  are 


THE  ROOT 


101 


dead  cells  but  are  sound  and  give  support  to  the  trees.  Souie- 
tiines  the  heart-wood  decays  aud  the  tree  becomes  hollow  but 
continues  to  live  and  grow  so  long  as  the  cambium  is  uninjured. 
The  root  (I'igs.  75  and  76)  is  composed  of  the  same  tissues 
as  the  stem^  but  they  are  arranged  in  an  entirely  different  man- 
ner. In  the  centre  is  the  central  cylinder  or  axis  made  up  of 
iibro-vascular  bundles  which  are  separated  by  thin  .layers  of 
parenchyma.  Immediately  surrounding  this  axis  is  a  compar- 
atively thick  zone  of  parenchyma  cells  known  as  the  cortex.   This 


Fig.  75 


Fig.  75. — Diagrammatic  longitudinal  section  of  root  tip  shewing:  a,  axis  cylinder;  c,  cortex; 

e,  epidermis;  x,  root  cap. 

Fig.  76. — Cross-section  of  root  tip  showing  cellular  structure  and  root-hairs. 


is  surrounded  by  a  very  thin  layer  of  cells  known  as  the  epi- 
dermis. The  epidermis  of  the  very  young  roots  gives  rise  to  a 
great  number  of  extremely  delicate  root  hairs  which  penetrate 
the  soil  and  take  the  water  and  necessary  substances  which  may 
be  in  solution.     (Page  26.) 


102 


ANATOMY  OF  STEMS.   ROOTS.  AND  LEAVES 


The  structure  of  the  leaves  varies  somewhat  in  the  different 
plants.  Probably  the  most  conmion  form  is  that  which  we  will 
describe.  The  typical  leaf  may  be  said  to  be  composed  of  four 
layers  of  parenchyma  cells  supported  by  delicate  frame  work 
of  fibro-vascular  bundles.  The  upper  layer  of  cells  is  the  upper 
epidermis  and  consists  of  thick-walled,  transparent  cells ;  below 
this  is  the  layer  of  columnar  or  palisade  cells  which  are  elon- 


FiQ.  77 


Fig.    77. — Cross-section  of  leaf  showing:  u,  upper  epidermis;  p,  palisade  cell 
ophyll  cells;  1,  lower  epidermis;  s,  stomata. 
Fig.  78. — Lower   surface   of  leaf   showing   stomata. 


s;  ni,  mes- 


gated,  more  or  less  cylindrical  and  placed  at  right  angles  to  the 
epidermal  layer;  just  below  the  palisade  layer  is  a  thick  layer 
of  loose,  irregularly  shaped  parenchyma  cells  known  as  the 
mesophyll;  just  below  the  mesophyll  is  the  last  layer  or  lower 
epidermis  which  is  very  similar  to  the  upper  epidermis.  The 
palisadq  cells  are  rich  in  protoplasm  and  in  the  green  coloring 
matter  which  is  known  as  the  chlorophyll.  The  chlorophyll  is 
usually  confined  to  very  definite  small  bodies  known  as  chloro- 
plasts  and  is  essential  for  the  photosynthesis  work  of  the  plant. 
(Page  115.) 


EXERCISES  SHOWING  MINUTE  STRUCTURES 


103 


In  the  lower  epidermis  will  be  found  a  considerable  number 
of  small  openings  or  stomata  (singular  stoma)    (Figs.  77  and 
78),  leading  into  the  irregular  tunnels  or  intercellular  spaces 
found    between    the    cells    of    the 
mcsophyll.      Each  stoma  or  open- 
ing is  between  two  crescent-shaped 
cells  called  guard  cells.     The  func- 
tion of  these  parts  will  be  consid- 
ered in  Chapter  X. 

Hair-like  Growth  on  Leaves. — 
The  leaves  of  some  plants  are  very 
smooth  while  others  have  more  or 
less  delicate  hair-like  growths 
known  as  trichomes,  (Fig.  79.) 
(Chapter  IV.)  These  trichomes 
are  so  numerous  on  the  leaves  of 
some  plants  as  to  give  them  the 
appearance  of  velvet.  These 
structures  are  also  found  on  the 
young  stems  of  many  plants.  They 
are  outgrowths  of  the  epidermal 
cells  and  present  numerous  very 
interesting  forms.  Some  of  them 
are  glandular  in  character,  and  cause  the  plant  to  feel  sticky  to 
the  touch.    They  are,  no  doubt,  protective  in  many  ways. 


Fig.  79. — Trichomes  or  plant  hair 
from  leaf  surface. 


EXERCISES  SHOWING  MINUT'E   STRUCTURES 


1.  Pith. — Cut  a  vpry  thin  section  of  a  pitli,  mount  in  a  drop  of 
alcohol  and  glycerine  and  examine  under  the  microscope.  Note  the 
large,  tliin-walled  parenchyma  cells  and  the  intercellular  spaces  between 
them.  Tliey  resemble  a  large  number  of  thin  hollow  balls  thrown  together 
and  slightly  pressed  out  of  shape  where  they  come  in  contact. 

2.  Examine  a  small  piece  of  algae  (preferably  Spirogyra)  iinder 
the  microscope.  Note  the  size  and  form  of  the  cells  and  the  chromato- 
phore. 


104  ANATOMY  OF  STEMS,  ROOTS,  AND  LEAVES 

3.  Examine  a  small  piece  of  algse  that  has  been  kept  in  alcohol  and 
stained  with  eosin.    Note  the  protoplasm  and  nucleus. 

4.  Examine  a  very  thin  section  of  potato  under  the  microscope  and 
note  the  starch  grains.     Stain  with  dilute  iodine  and  examine  again. 

5.  Cut  a  very  thin  crossi-section  from  the  pith  of  corn  stalk.  Note 
the  parenchyma  cells  and  the  fibro-vascular  bundles.  Study  out  the  parts 
as  indicated  in  the  figures. 

l>.  Geranium  Stem. — Cut  a  very  thin  cross-section  of  the  stem  of  a 
geranium.     Note  tlie  parts  as  indicated  in  Figs.  G7,  70. 

7.  Woody  Stem.- — Cut  a  very  thin  cross-section  of  a  twig  from  a 
tree.     Note  tlie,  ])artii  as  indicated  in  Fig.  74. 

8.  Many  Forms  of  Cells.— Make  longitudinal  sections  of  all  of  the 
above  stems  and  find  as  many  kinds  of  cells  as  possible. 

!••  Leaf  Structure. — Hold  a  bit  of  a  leaf  between  two  pieces  of  pith 
and  cut  very  thin  cross-sections.  Examine  under  the  miscroscope  and  note 
tlie  parts  as  indicated  in  Fig.  77. 

10.  Peel  small  fragments  of  epidermis  from  both  lower  and  upper 
surfaces  of  a  leaf  and  examine  under  the  microscope. 

11.  Root  Structure. — Hold  a  young  root  from  corn  or  bean  between 
two  pieces  of  pith  and  cut  very  thin  cross-sections.  Examine  under  the 
microscope  and  note  the  i^arts  as  indicated  in  Figs.  75  and  76. 

QUESTIONS 

L  Wliat  do  you  understand  by  fibro-vascular  bundles? 

2.  How  are  tliey  arranged  in  the  plant? 

3.  What  do  you  understand  by  plant  cell? 

4.  What  are  some  of  the  difl'erent  kinds  of  plant  cells? 

5.  What  do  you  understand  by  protoplasm? 

6.  What  else  do  you  find  in  plant  cells? 

7.  Wliat  is  the  cambium?     Where  is  it  located? 

8.  Explain  the  difference  between  mono-  and  dicotyledonous  stems. 

9.  What  is  meant  by  phloem  and  xylem?     Where  are  they  located? 

10.  What  are  the  medullary  rays?  , 

11.  What  are   annular   rays? 

12'.  What  is  meant  by  epidermis? 

13.  In  what  parts  of  the  plant  do  you  find  chlorophyll? 

14.  What  is  meant  by  mesophyll  ? 

15.  What  and  where  are  the  trichomes? 


CHAPTER  IX 
CHEMICAL  COMPOSITION  OF  THE  PLANT 

We  have  examined  both  young  and  mature  plants  and  have 
studied  the  various  organs  of  which  they  are  composed.  We 
have  also  learned  something  of  the  structure  of  these  plant 
organs.  Let  us  learn  something  of  their  chemical  composition ; 
something  about  the  qualities  that  make  them  useful  or  unfit 
for  food  and  other  purposes.  Of  course,  we  have  reason  to  believe 
that  the  different  parts  of  the  plant  are  unlike  in  chemical  com- 
position, for  we  know  that  they  are  difi'erent  in  structure  and 
texture,  and  that  we  use  them  for  radically  diiferent  purposes. 

Water,  Avhich  is  so  essential  for  plant  growth  (Chapter  I) 
is  the  most  abundant  and  one  of  the  most  important  compounds 
in  the  plant.  We  know  that  fruits  and  vegetables  are  juicy  and 
we  have  seen  the  bleeding  of  trees  when  pruned  too  late  in  the 
season,  and,  therefore,  it  is  not  necessaiy  to  demonstrate  that 
plants  contain  water.  The  quantity  of  water  in  the  diiferent 
parts  of  the  plant  varies  from  the  very  large  amounts  in  juicy 
fruits  to  the  very  small  amounts  in  dry  grains.  The  following 
table  shows  some  of  the  extremes : 

Percentage  of  mater  content 
Plant  hy  weight 

Cucumber    ( fruit)     96 

Cabbage    ( leaves )    90 

Beets,  red    (roots)     88.5 

Apples    (fruit) 83.2 

Potato    (Irish)    78.9 

Potato  (sweet)    ' 71.1 

Corn    (green  fodder)    79.8 

Corn   ( dry  grain )    10.9 

We  also  know  that  plants  contain  carbon,  for  we  have  seen 
the  charcoal  which  is  fonued  as  a  result  of  burning  a  piece  of 

105 


106  CHEMICAL  COMPOSITION  OF  THE  PLANT 

wood.  But  when  the  fragment  of  charcoal  is  burned  we  have  a 
few  ashes  remaining.  The  chemist  tells  that  this  ash  contains 
small  quantities  of  phosphorus,  potassium,  calcium,  mag- 
nesium, sulphur,  sodium,  chlorine,  manganese,  aluminum,  etc. 
The  water,  carbon  and  nitrogen  which  we  know  make  up  a  con- 
siderable part  of  the  plant  have  been  carried  oti"  as  vapor  and 
gas  during  the  process  of  burning. 

The  Avater  is  composed  of  two  gaseous  elements,  hydrogen 
and  oxygen.  When  wood  burns  or  decays,  the  carbon  (C  )  unites 
with  the  oxygen  (O)  of  the  air  forming  a  gaseous  compound 
known  as  carbon  dioxide  (COo),  which  is  available  for  new 
plant  growth.     (Page  115.) 

Starch. — We  also  know  that  plants  contain  starch  W'hich  is 
composed  of  three  elements,  carbon,  hydrogen  and  oxygen,  com- 
bined as  C^HioOg.  Starch  is  one  of  the  most  abundant  plant 
substances  and  is  one  of  the  valuable  plant  products  of  com- 
merce. It  constitutes  a  considerable  part  of  the  dry  substance 
of  seeds,  green  fruits,  fleshy  roots,  tubers,  bulbs,  fleshy  leaves, 
etc.,  in  which  it  can  be  readily  detected  by  very  simple  experi- 
ments. Starch  is  one  of  the  important  food  substances  for  both 
man  and  beast.  Potatoes,  sweet  potatoes  and  other  tubers  and 
fleshy  roots  contain  large  quantities  of  starch.  Grains,  peas, 
beans  and  other  seeds  contain  an  abundance  of  starch.  The 
starch  not  only  makes  these  plants  valuable  for  food  but  also  for 
other  purposes.  Tapioca,  some  forms  of  paste  and  other  ar- 
ticles of  commerce  are  made  from  starch.  The  following  table 
shows  the  relative  amount  of  starch  found  in  some  common  food 
plants,  as  estimated  in  percentage  of  dry  weight. 

Plant  products  Percentage  of  starch 

Seeds  of  navy  beans   45 

Seeds  of  i>eas  52 

Seeds  of  corn   fiO 

Seeds  of  wheat GS 

Seeds  of   rice    68 

Thibers  of  potatoes    80 


FAT8  107 

The  starch  is  found  in  definite  bodies  known  as  starch 
grains  within  the  cells  of  the  plant,  and  can  be  seen  readily 
with  the  aid  of  the  microscope.  The  size  and  form  of  the  starch 
grains  vary  in  different  plants. 

Sugar  is  another  plant  product  very  similar  to  starch,  but 
it  occurs  in  a  much  greater  variety  of  forms.  The  most  com- 
mon type  is  the  cane  sugar  (CoHioOg)  which  is  abundant  in 
many  plants  and  forms  a  valuable  food  product.  It  is  found 
in  the  cell-sap  and  can  be  readily  detected  by  simple  experiments. 
It  is  especially  abundant  in  sugar  beets,  sugar  maple,  sugar 
cane  and  ripened  fruits.  We  all  recognize  the  value  of  sugar 
for  food  and  as  an  article  of  commerce.  One  of  the  great  prob- 
lems of  the  plant  breeders  is  to  increase  the  percentage  of 
sugar  in  the  sugar-producing  plants.  (Chapter  XV.)  The 
amount  of  sugar  in  the  sugar  beet  has  been  increased  from  7 
to  15  per  cent  by  scientific  methods  of  plant  breeding. 

Carbohydrates, — The  cell-walls  are  composed  of  cellulose 
which  is  made  up  of  the  same  elements  as  starch  and  sugar,  but 
they  are  also  infiltrated  with  various  other  substances.  Cellu- 
lose is  the  most  important  plant  compound  in  the  manufacture 
of  paper.  Cellulose  is  also  used  extensively  in  the  manufacture 
of  the  many  celluloid  articles  on  the  market,  and  it  is  also  used 
in  the  making  of  gun  cotton  and  other  high  explosives.  Many 
plants  also  produce  gums  which  are  composed  of  these  same 
elements  and  some  of  which  are  important  articles  of  com- 
merce. The  starch,  sugar,  gums,  and  cellulose  are  known  as 
carbohydrates ;  that  is,  their  hydrogen  and  oxygen  is  always  in 
the  ratio  of  two  to  one. 

Fats. — Many  plants  also  contain  fats  and  oils  which  are 
composed  of  the  same  elements  as  the  carbohydrates  (i.e.,  hydro- 
gen and  oxygen),  but  the  hydrogen  and  oxygen  ratio  is  never 
two  to  one.  The  fats  and  oils  are  known  as  hjjdrocarhons  and 
are  usually  most  abundant  in  the  seeds,  especially  nuts.     They 


108  CHEMICAL  COMPOSITION  OF  THE  PLANT 

are  used  for  food,  medicine,  soap  making  and  many  other  pur- 
poses and  are  among  the  most  important  articles  of  commerce. 

Proteins. — Plants  also  contain  a  third  group  of  foods,  known 
as  proteins  or  proteid  foods  which  are  composed  of  carbon, 
hydrogen,  oxygen  and  nitrogen,  and  are  among  our  most  im- 
portant food  substances.  They  are  especially  abundant  in  seeds 
and  the  food  value  of  many  plants  over  others  depends  almost 
entirely  on  their  percentage  of  protein.  They  may  be  associated 
with  the  carbohydrates,  but  in  some  cases  are  borne  in  separate 
cells.  The  great  value  of  clover,  cowpeas,  soybeans  and  related 
plants  for  stock  feed,  and  of  beans  and  peas  as  food  for  man 
depends  primarily  on  their  protein  content. 

Plants  contain  many  other  compounds,  some  of  which  are 
referred  to  as  waste  products.  Among  the  most  important  of 
these  compounds  are  the  following: 

(a)  The  essential  (or  volatile)  oils,  w^hich  are  entirely 
different  from  the  true  oils  previously  referred  to.  They  may 
occur  in  any  part  of  the  plant,  but  are  especially  abundant  in 
the  foliage  and  flowers.  Most  of  the  odors  of  plants  are  due  to 
these  essential  oils,  many  of  which  are  extracted  and  used  in 
the  manufacture  of  medicines,  perfumes,  soap  and  other  articles 
of  commerce. 

(b)  Gums  and  resins  of  various  kinds  are  familiar  articles 
of  commerce.  Among  the  most  important  are  turpentine,  resin, 
balsams,  gum-camphor,  gum-arabic  and  gum-tragacanth. 

(c)  Organic  acids  are  very  numerous  and  are  especially 
abundant  in  certain  fruits.  Among  the  most  common  organic 
acids  of  commerce  are  oxalic,  malic,  tartaric  and  citric  acids. 

(d)  Tannins  are  abundant  and  are  found  in  the  great  ma- 
jority of  the  higher  plants.  They  are  used  for  the  making  of 
hides  into  leather,  in  medicines  and  for  other  purposes. 

(e)  Alkaloids  are  abundant  plant  products  from  which  we 
obtain  many  valuable  medicines  and  some  of  our  most  danger- 


EXERCISES,  COMPOSITION  OF  PLANT  TISSUES  109 

ous  poisons.  Among  the  most  familiar  are  quinine,  strychnine, 
cocaine  and  morphine.  In  this  connection,  it  is  well  to  remem- 
ber that  about  90  per  cent  of  our  medicines  are  of  plant  origin 
and  that  much  of  the  early  work  in  botany  was  for  the  discovery 
of  new  drug  plants  with  which  to  relieve  the  sufferings  of 
mankind. 

EXERCISES   SHOWING  THE   COMPOSITION   OF  PLANT  TISSUES 

1.  Ash  in  Leaves. — Weigli  a  bunch  of  green  cabbage  or  lettuce  leaves. 
Dry  tliem  in  an  oven.  Weigli  again  and  compute  percentage  of  water. 
Burn  tlie  leaves,  weigli  and  compute  the  percentage  of  ash. 

2.  Water  in  Seeds. — Ptit  a  few  seeds  in  a  test  tube,  plug  with  cotton 
and  heat  gently  so  as  not  to  scorch  the  seeds.  Hold  the  tube  as  nearly 
horizontal  as  possible  while  heating.  Do  you  see  signs  of  water  on  the 
glass? 

3.  Ash  in  Wood. — Put  a  piece  of  wood  in  a  test  tube  and  heat  until 
a  piece  of  charcoal  (carbon)  is  formed.  Burn  the  charcoal  to  ashes. 
Shake  tha  ashes  in  water.     Do  they  dissolve? 

4.  Tests  for  Starch  and  Sugar. — Put  a  little  commercial  starch  and 
a  little  sugar  in  separate  test  tubes  of  water,  and  shake.  Do  they  both  dis- 
solve? Add  a  few  drops  of  iodine  to  the  starch  and  note  the  change  in 
color.  This  is  the  test  for  starch.  Add  a  small  amount!  of  Fehling's  fluid, 
a  few  drops  at  a  time;  a  brick  red  color  indicates  the  presence  of  sugar. 
This  test  will  not  work  with  cane  sugar  unless  the  solution  has  been 
boiled  with  dilute  acid  before  adding  the  Fehling's    fluid. 

Fehling's  solution  can  be  made  in  the  laboratory.  It  consists  of  two 
solutions:  (A)  30.04  grams  of  pure  powdered  copper  sulpliate  in  200  c.c. 
of  water.  {B)  150  grams  of  Rochelle  salt  and  50  grams  caustic  soda  in 
500  c.c.  of  water. 

Keep  the  two  solutions  separate  and  mix  before  using  as  follows: 
2  parts  of  solution  A. 
5  parts  of  solution  B,. 
10  parts  of  water. 

5.  Carbon  in  Sugar. — Put  a  little  sugar  in  a  test  tube  and  heat 
slowly  until  you  have  a  black  mass  of  carbon.  Note  what  occurs  during 
the  process  and  explain. 

6.  Testing  Seeds  and  Fruits. — Test  fruits,  tubers,  fleshy  roots  and 
various  other  parts  of  plants  by  applying  the  starch  and  sugar  tests  to 
freshly  cut  surfaces. 

7.  Examining  Potatoes  and  Apples. — Cut  very  small,  thin  slices  of 


no  CHEMICAL  COMPOSITION  OF  THE  PLANT 

potato  and  apple,  mount  in  water  and  examine  under  the  microscope.  Add 
a  drop  of  iodine  and  not*»  the  effect. 

8.  Starch  and  Sugar  after  Germination.— Crush  a  few  well  ger- 
minated seeds  and  put  in  two  test  tubes,  fill  about  one-third  full  of  water 
and  shake  thoroufilily.     l?oil  and   test  for  starch  and  sugar. 

0.  Changing  Starch  to  Sugar. — Make  a  thin  paste  by  boiling  starch 
in  two  test  tuljes  of  water.  Allow  to  cool  and  add  a  small  amount  of 
diastase  or  saliva  to  one.  Keep  in  a  warm  place  for  24  hours  and  te^ 
both  for  sugar. 

10.  Oil  in  Seeds. — Crush  a  seed  of  castor  bean  or  the  kernel  of  some 
nut  between  tlie  fingers  and  thumb  and  note  the  oily  character.  Rub  the 
seed  or  nut  on  a  piece  of  paper  for  the  same  purpose.  Tie  a  small  amount 
of  cruailied  seeds  or  other  plant  material  in  a  bit)  of  cheese-cloth  and  soak 
in  a  small  dish  of  benzine;  squeeze  and  remove  and  allow  the  benzine  to 
evaporate.  Any  oil  that  may  be  present  will  be  found  in  the  dish.  Make 
a  list  of  vegetable  oils  of  commercial  importance  and  give  their  sources. 

11.  Protein  in  Flour. — Tie  a  small  quantity  of  wheat  flour  in  a  bag 
and  knead  under  a  stream  of  water.  Tlie  sticky  dough  that  remains  is 
largely  protein.  Tlie  starch  was  mostly  washed  out  by  the  stream  of 
water. 

12.  Starch  and  Protein  in  Wheat.— Cut  very  thin  slices  of  wheat 
grain  and  examine  under  the  microscope.  Test  for  starch.  Note  that 
tlie  starch  is  in  the  center  and  in  very  thin-walled  cells.  Also  note  that 
the  proteid  (aleuronc)  is  in  cells  surrounding  the  starch.  Also  note  the 
hull  is  made  up  of  the  union  of  seed  and  ovary  coats. 

QUESTIONS 

1.  \\']iat  compound  is  found  in  greatest  amount  in  the  jilant?  How 
does  it  get  into  the  plant?  Is  the  total  amount  entering  the  plant  retained? 
If   not,   how  does   it  pass  out? 

2.  Explain  the  results  obtained  in  the  drying  and  burning  of  a 
piece  of  wood.  How  do  these  elements  and  compounds  become  a  |»art  of 
the  wood? 

3.  What  substances  found  in  plants  are  useful  as  foods  for  animals? 
In  what  parts  of  the  plant  are  they  found? 

4.  Give  a  list  of  commercial  products  of  plants.  Tell  where  found 
and  their  uses. 

5.  Mention  several  plants  or  products  rich  in  sugar, 
fi.  From  what  plants  is  starch  obtained  commercially? 

7.  What  plants  yield  oil  for  commerce? 

8.  ]\Iention  several  stock  feeds  rich  in  protein. 


i 


CHAPTER  X 
PLANT  FOODS  AND  PLANT  GROWTH 

We  have  learned  something  about  the  important  substances 
found  in  phmts,  the  starches,  sugar,  oils  and  proteids  which  make 
them  valuable  for  food.  We  have  also  learned  that  they  con- 
tain many  other  substances  of  more  or  less  value  in  commerce. 
We  also  know  that  many  plants  are  gi-own  for  their  fibre  which 
is  used  in  many  manufacturing  industries,  and  we  also  use  the 
wood  of  many  of  the  larger  plants  for  many  purposes.  There- 
fore, it  is  very  evident  that  the  plant  kingdom  produces  a  very 
large  number  of  useful  plants.  Let  us  now  study  the  source  of 
these  products  and  the  processes  by  which  they  are  formed. 

Plants  are  unlike  animals  in  that  they  use  comparatively 
simple  compounds  which  are  obtained  from  the  soil  and  air  and 
transformed  into  true  food  materials  for  their  own  gi-owth ; 
animals  cannot  use  such  simple  compounds,  but  are  compelled 
to  feed  upon  plants  from  which  they  secure  already  manufac^ 
tured  or  true  foods,  carbohydrates  and  proteids.  Therefore,  all 
animal  life  is  dependent  either  directly  or  indirectly  on  plant 
life  for  its  existence.  The  most  important  raw  foods  or  com- 
pounds that  the  plant  gets  from  the  earth  are  water  (H2O), 
ammonia  compounds  (Nil.,),  sulphur,  potassium  and  phos- 
phorus, and  various  salts.  The  most  important  raw  foods  from 
the  air  are  carbonic  acid  gas  or  carbon  dioxide  (COo)  and  very 
small  amounts  of  oxygen  (O). 

The  energy  with  which  these  raw  materials  are  transformed 
into  true  foods  comes  from  the  sun  in  the  form  of  heat  and  light. 
Therefore,  all  life  (both  plant  and  animal)  upon  the  earth  is 
dependent  upon  the  sun  for  its  existence.  These  raw  foods  are 
transformed  into  true  foods  in  the  plant  before  they  can  be 

111 


112  PLANT  FOODS  AND  PLANT  GROWTH 

used  even  for  its  own  growth.  However,  the  process  by  which 
these  simple  compounds  are  transformed  into  true  food  materials 
is  imperfectly  understood. 

The  amount  of  water  in  the  soil  varies  with  the  amount  of 
rainfall  and  the  texture  of  the  soil.  Coarse,  sandy  soils  are  poor 
retainers  of  waiter  as  compared  with  the  very  fine  clay  soils. 
Humus  soils  are  excellent  retainers  of  water,  and  this  fact, 
together  with  their  richness  in  organic  matter,  makes  them  espe- 
cially good  for  agricultural  purposes.  It  is  very  evident  that 
water  acts  as  a  solvent  for  the  available  soil  substances  and  salts, 
and  is  then  taken  up  by  the  root-hairs.  We  have  already 
studied  the  root-hairs,  and  know  that  they  are  long,  delicate  cells 
containing  very  active  living  protoplasm  and  a  watery  sub- 
stance called  cell-sap.  This  cell-sap  is  -water  containing  salts, 
acids  and  sugars.  The  root-hairs  are  evidently  well  filled  and 
somewhat  distended.  When  cells  are  distended  in  this  man- 
ner they  are  said  to  be  turgescent,  or  in  a  state  of  turgor.  All 
the  active  cells  of  a  normal,  growing  plant  are  turgid  and  it  is 
this  condition  which  enables  the  soft  parts  of  a  plant  to  main- 
tain their  form  and  position.  When  cells  lose  their  turgidity 
the  plants  wilt. 

Osmosis. — It  is  well  known  that  when  a  substance  dissolves 
in  a  liquid  it  gradually  diffuses  until  equally  distributed. 
If  two  solutions  of  equal  density  are  separated  by  a  plant  or 
animal  membrane,  the  substances  in  solution  will  gradually  dif- 
fuse through  the  membrane  until  the  two  solutions  are  uniform 
throughout.  This  is  known  as  os/ho.s/.s.  (Fig.  80.)  If  two  solu- 
tions of  unequal  density  are  used  there  will  be  a  flow  from  the 
less  dense  to  that  of  the  greater  density.  Wlien  a  plant  is 
growing  under  suitable  conditions,  the  solution  of  greater  dens- 
ity is  within  the  cells,  especially  the  root-hairs ;  and  the  solution 
of  lesser  density  surrounding  them.  The  delicate  root-hairs 
ramify  among  the  extremely  fine  particles  of  soil.     The  soil, 


OSMOSIS 


113 


water  aiid  the  salts  in  solution  pass  into  the  cells  of  the  root- 
hairs  and  thence  into  the  fibrous  and  tracheary  tissues  of  the 
root  and  thence  through  the  same  and  probably  other  tissue  of 
the  sap  wood  of  the  stem  into  the  leaves  where  a  considerable 
part  of  it  is  given  off  by  transpiration.  (Chapter  VIII.)  The 
exact  process  by  which  water  passes  through  a  growing  plant  is 


FiQ.  80. — Apparatus  for  demonstrating  osmosis;  thistle  tube  on  left  and  egg  on  right. 

not  understood.  Some  of  the  acid  within  the  root-hairs  passes 
out  (exosmosis)  and  helps  to  dissolve  the  raw  food  compounds 
in  the  soil,  thus  making  them  more  available.  If  the  character 
of  the  soil  is  such  that  the  water  solution  is  of  greater  density 
than  the  contents  of  the  plant  cells,  the  plant  cannot  live  in  it, 
and  if  a  plant  should  be  set  in  such  soil  it  would  wilt  very 
quickly  because  of  the  loss  of  water  which  would  pass  out  to 
the  soil. 
s 


114  PLANT  FOODS  AND  PLANT  GROWTH 

Transfer  of  Water. — The  process  by  which  water  is  trans- 
ferred from  one  part  of  the  plant  to  another  part  is  very  imper- 
fectly understood,  but  we  do  know  that  it  is  transferred  from 
place  to  place  and  t-uat  it  is  carried  upward  in  great  quantities 
against  the  tremendous  force  of  gravity.  We  know  that  the 
force  necessary  to  lift  this  column  of  water  to  the  top  of  very 
tall  trees  must  be  enormous.  We  know  also  that  this  activity 
is  much  greater  at  certain  seasons  of  the  year  than  at  others. 
We  have  all  observed  the  bleeding  of  trees  and  vines  when 
pruned  too  late  in  the  spring,  and  know  that  considerable  injury 
may  result  from  this  practice. 

Transpiration. — We  have  said  that  a  considerable  amount 
of  water  is  given  oif  through  the  leaves  by  transpiration.  This  is 
also  true  of  the  new  shoots  and  such  other  green  parts  as  the 
plant  may  possess.  The  transpiration  of  water  should  not  be 
confused  with  evaporation.  The  latter  process  takes  place  from 
the  free  surface  of  a  body  of  water  and  is  controlled  by  the 
physical  conditions  of  the  air,  but  the  former  is  controlled  by 
the  structural  character  of  the  plant  and  the  living  protoplasm 
of  the  plant  cells.  The  water  in  the  plant  must  pass  through 
the  cell-walls  into  the  intercellular  spaces  of  the  mesophyll  to 
which  we  have  previously  referred  (Chapter  IV),  and  then 
passes  out  through  the  stomata  by  a  process  of  diffusion. 

Of  course,  when  the  air  is  dry  the  transpiration  of  water  will 
be  much  greater  than  when  moist.  The  number  of  stomata 
varies  greatly  in  different  species  of  plants,  those  growing  in 
dry  places  usually  having  fewer  than  those  growing  in  wet  places. 
The  amount  of  water  which  plants  take  from  the  soil  and  give 
out  through  the  leaves  during  a  growing  season  is  enormous, 
but  extremely  variable  when  we  compare  plants  living  under 
different  conditions.  It  is  estimated  that  some  of  our  common 
farm  crops  take  up  and  give  off  an  average  of  300  pounds  of 
water  in  the  production  of  one  pound  of  dry  material,  although 
in  some  plants  it  is  three  times  this  amount. 


THE  FORMATION  OF  CARBOHYDRATES  115 

A  Change  of  Gases. — The  giviug  olt'  of  water  through  the 
stomata  is  associated  with  a  change  of  gas  by  transfusion  be- 
tween the  air  within  the  intercellular  spaces  of  the  leaf  and  the 
air  on  the  outside.  Therefore,  as  the  water  passes  outward 
through  the  stomata,  the  carbon  dioxide  (CO2)  of  the  air  passes 
into  the  intercellular  spaces,  is  absorbed  by  the  protoplasm  of 
the  mesophyll  cells  and  immediately  dissolved  in  the  cell  sap, 
thus  forming  carbonic  acid  (COa+HaO^CHaOg).  The  action 
of  the  sunlight  on  the  chlorophyll  results  in  the  breaking  up  of 
this  carbonic  acid  and  the  recombination  of  the  elements  with 
the  elements  of  water  into  other  compounds.  This  delicate  and 
complicated  process  is  very  imperfectly  understood,  and  the 
first  result  that  we  can  recognize  with  any  degree  of  certaint}^ 
is  glucose  or  grape  sugar  (C,;H,oO,;). 

Plants  and  Animals  Help  Each  Other.^We  know  that  the 
process  results  in  the  liberation  of  free  oxygen  (6CO2  +  6H0O 
^C6H^206+120)  which  is  given  out  through  the  stomata  and 
is  essential  for  the  life  of  animals.  Therefore,  we  see  that  ani- 
mal and  plant  life  are  more  or  less  inter-dependent,  but  it  is 
very  evident  that  animals  are  more  dependent  upon  plants  than 
plants  are  upon  animals.  Plants  utilize  the  carbon  dioxide 
which  is  exhaled  by  the  animals,  but  they  could  readily  obtain 
this  supply  from  other  sources.  Animals  utilize  the  oxygen 
given  off  by  plants,  and  are  absolutely  dependent  upon  plants 
for  their  food  supply. 

The  formation  of  carbohydrates,  that  is,  starches  and 
sugars,  from  these  crude  materials  (water  and  carbon  dioxide) 
by  the  action  of  sunlight  on  the  chlorophyll  is  known  as  photo- 
synthesis and  is  the  most  wonderful  and  most  mysterious  process 
in  all  nature.  With  this  as  a  beginning,  we  have  the  basis  for 
the  formation  of  innumerable  other  plant  and  animal  products. 
A  small  part  of  this  organized  food  is  used  immediately  for  cell 
formation  and  growtli,  but  the  greater  part  is  stored  for  fu- 
ture use. 


116  PLANT  FOODS  AND  PLANT  GROWTH 

Grape  sugar  Avliicli  is  formed  in  the  green  parts  of  plants 
can  be  readily  transformed  into  starch  by  the  loss  of  one  molecule 
of  water  (C,;HioOo  —  H2O  =  CcHioOg).  In  some  plants, 
such  as  the  sugar  beet  and  sugar  corn,  the  sugar  is  transferred 
directly  and  stored  as  such  without  change.  But  in  most  plants 
it  is  very  quickly  transformed  into  starch,  which  is  reconverted 
into  sugar  during  the  night  and  transferred  to  other  parts. 
Therefore,  if  the  leaves  are  examined  early  in  the  afternoon  they 
will  be  found  to'  be  very  rich  in  starch  as  compared  with  their 
condition  before  sunrise. 

Other  Organic  Compounds  Formed. — We  know  that  search 
and  sugars  are  the  most  abundant  food  products  of  the  plant; 
that  they  are  especially  abundant  in  vegetables,  fruits  and  seeds. 
But  we  also  know  that  there  are  other  substances,  such  as  hydro- 
carbons (fats  and  oils)  ;  and  the  proteins,  which  contain  nitro- 
gen (and  some  sulphur  and  phosphorus).  These  are  among  the 
most  important  food  products,  but  we  know  very  little  about 
their  formation. 

Mineral  Substances. — Plants  take  a  great  many  minerals 
from  the  soil.  The  most  important  are  phosphorus,  potassium, 
calcium,  magnesium,  sulphur,  iron,  sodium,  chlorine,  silicon, 
manganese  and  aluminum.  These  elements  go  into  solution  in 
the  water  of  the  soil  and  then  pass  into  the  root-hairs  in  the 
manner  already  described.  They  may  be  found  by  making 
a  chemical  analysis  of  the  ash  of  the  plant.  They  vary  in  pro- 
portion in  different  species  of  plants,  in  plants  at  diiferent  ages 
and  in  different  parts  of  the  same  plant. 

These  minerals  exist  in  varying  quantities  in  the  soil,  but 
their  proportions  may  not  be  such  as  are  needed  by  the  crop, 
or  they  may  not  be  in  such  form  as  to  be  available  as  plant  food. 
Therefore,  the  progressive  farmer,  who  is  familiar  with  his 
soil  and  with  the  needs  of  his  crop,  makes  use  of  manures 
and  commercial  fertilizers  to  overcome  these  deficiencies. 

Nitrogen  and  Protein. — One  other  most  important  element 


IMPORTANCE  OF  HUMUS 


117 


of  plant  food  wliicli  we  have  not  taken  into  consideration  is 
nitrogen^  an  element  which  is  essential  in  the  formation  of 
protoplasm  and  protein.  The  food  value  of  many  plants  de- 
pends upon  their  protein  content.  I^itrogen  constitutes  78  per 
cent  of  the  atmosphere,  and  one  might  readily  suppose  that  the 
plant  could  secure  its  supply  from 
that  source.  But  such  is  not  the 
case.  The  free  nitrogen  of  the  air 
is  not  available  for  plant  food.  It 
must  be  united  with  hydrogen  to 
form  a  nitrate  before  it  can  be  uti- 
lized by  the  growing  plant.  There 
are  several  sources  of  nitrogen  for 
plant  food. 

(a)  By  the  decay  or  disintegra- 
tion of  organic  matter;  i.e.j  dead 
plants  and  animals  and  their  waste 
products.  This  is  brought  about  by 
millions  of  minute  organisms  of 
decay  known  as  bacteria. 

(6)  By  certain  soil  bacteria 
which  live  in  the  tubercles  or  no- 
dules (Fig.  81)  on  the  roots  of  legu- 
minous plants  and  which  enable  the 
plant  to  take  the  nitrogen  from  the 
hydrogen,   thus  forming  ammonia  compounds. 

(c)  By  rainfall,  which  carries  tlie  nitrogen  of  the  air  to  the 
soil  where  it  becomes  available  for  these  bacteria. 

(d)  By  electrical  discharges  (lightning)  producing  nitrous 
and  nitric  acids  which  are  carried  to  the  earth  by  the  rainfall. 
The  first  and  second  of  these  are  the  most  important. 

Importance  of  Humus. — The  first  of  these  sources  shows 
the  importance  of  utilizing  animal  manures  and  decaying  plant 
materials  as  fertilizers.     These  decayed  animal  and  plant  prod- 


FiG.  81. — Root  of  legume  showing 
tubercles. 


lir,  and  combine  it  with 


118  PLANT  FOODS  AND  PLANT  GROWTH 

nets  are  called  Jiunius,  and  we  Lave  long  recognized  that  liunms 
is  essential  for  plant  growth.  The  second  shows  the  importance 
of  the  use  of  leguminous  plants  to  increase  the  nitrogen  content 
of  the  soil  and  explains  why  clovers,  alfalfa,  cowpeas,  soybeans, 
vetch  and  similar  plants  are  of  such  great  importance  as  soil 
improvers. 

Circulation. — Knowing  that  plants  take  in  water  from  the 
soil,  that  it  rises  through  the  plants  and  is  given  off  through  the 
foliage,  naturally  indicates  that  the  plant  possesses  a  circulatory 
system  similar  to  that  of  animals.  Although  the  circulation  is 
through  definite  parts  of  the  plant  tissues,  it  is  not  through  a 
definite  set  of  tubes  and  does  not  have  a  propelling  organ  or 
pump  such  as  the  heart  of  the  animal.  The  water  rises  in  the 
wood  (or  xylem)  part  of  the  stem  and  carries  the  mineral 
substances  of  the  soil  in  solution.  But  this  does  not  complete 
the  problem  of  circulation.  Very  little  of  the  manufactured 
plant  food  is  stored  in  the  parts  in  which  it  is  formed  but  is 
transferred  to  fruits,  seeds,  tubers,  bulbs,  roots  and  other  parts 
for  storage.  This  transfer  is  primarily  through  the  outer  (or 
phloem)  part  of  the  stem.  We  do  not  understand  just  how 
this  transfer  is  accomplished,  but  much  of  the  food  must  undergo 
modifications,  must  become  soluble,  before  it  can  be  moved. 
The  carbohydrate  is  probably  moved  while  in  the  form  of  sugar 
(glucose),  and  the  fats  and  true  soils  as  glycerine  and  fatty 
acids,  and  the  proteids  in  a  form  known  as  amides. 

EXERCISES    SHOWING    PROCESSES    IN    PLANT    GROWTH 

1.  Osmosis  Through  a  Bladder. — Tie  a  bit  of  bladder  or  sausage 
casing  or  parchment  over  the  large  end  of  a  thistle  tube;  partly  fill  the 
tube  with  molasses  and  immerse  the  large  end  in  water  until  tlie  two 
liquids  are  on  a  level.  Make  observations  at  intervals  of  one  hour  and 
explain  tlie  phenomena. 

2.  Exosmosis  and  Endosmosis- — Peel  some  fleshy  root  such  as  car- 
rot, turnip  or  beet  and  cut  in  slices  about  %  x  1^,4  inches  and  about  Vs 
inch  in  thickness.  Put  a  few  of  them  in  distilled  water  and  a  few  in  a 
salt  or  sugar  solution.     Examine  after  a  few  hours  and  explain.     Now 


EXERCISES  SHOWING  PROCESSES  IN  PLANT   GROWTH   119 

transfer  tliem,  putting  those  that  were  in  the  solution  in  the  distilled 
water,  and  those  that  were  in  the  water  in  the  solution.  Examine 
after  a  few  hours  and  explain. 

3.  Movement  of  Plant  Fluids. — Cut  *  a  stem  of  a  Begonia  two 
or  three  inches  from  the  surface  of  the  soil,  and  place  the  severed  part 
in  a  glass  of  water  that  has  been  colored  with  some  analine  dye  or  red 
ink.  After  twenty-four  hours,  remove  and  cut  the  stem  at  various  points 
and  examine.  Fasten  a  small  glass  tube  on  the  stump  by  means  of 
adhesive  tape,  and  keep  the  roots  well  watered.  Note  the  rise  of  water 
in  the  tube.     Explain. 

4.  Transpiration. — Take  a  small  actively  growing  plant  and  tie  a 
piece  of  sheet  rubljer  over  the  pot  allowing  the  plant  to  project  through  a 
small  opening;  invert  a  glass  over  the  plant  and  note  the  moisture  which 
collects  within  the  next  few  hours.  Where  did  it  come  from?  Cut  a 
bunch  of  fresh  growing  plants  or  a  cabbage  and  weigh.  Allow  to  wilt 
and  dry  and  then  weigh  again.  Dry  in  an  oven,  but  do  not  char,  and 
weigh  again.     Explain. 

5.  Plant  Food. — Secure  a  quantity  of  coarse,  clean  sand,  and  fill  two 
flower  pots  or  cans  of  equal  size  witli  equal  quantities.  Plant  several  grains 
of  corn  of  approximately  the  same  size  and  character  in  each.  Water 
one  from  time  to  time  with  rain  water  or  distilled  water  and  the  other 
with  soil  solution.  Soil  solutions  may  be  prepared  by  filling  a  larga  pail 
two-thirds  full  of  rich  soil  or  well  rotted  manure  and  then  adding  enough 
water  to  make  a  thin  slop.  Stir,  allow  to  settle  and  draw  off  the  water. 
I'efill  witli  water  and  allow  to  stand  until  needed  again.  In  which  pot 
do  the  plants  grow  best?     Why? 

6.  Moisture  in  Wood. — Weigh  a  piece  of  green  wood.  Heat  until 
thoroughly  dry.     Weigh  again.     What  has  it  lost  and  how  much? 

7.  Carbon  in  Wood. — Burn  the  wood  imtil  charcoal  is  formed.  This 
is  almost  pure  carbon.     Weigh  again.    What  has  been  lost  and  how  much? 

8.  Ash  in  Wood. — Burn  the  charcoal.  What  have  you  remaining 
and  how  much? 

9.  Carbon  in  Sugar. — Put  a  little  white  sugar  in  a  test  tube  and 
heat.     What  happens?     Explain. 

10.  Study  of  Oxygen. — Mix  a  teaspoonful  of  potassiiun  chlorate 
with  about  one-fourth  the  amount  of  finely  powdered  manganese  dioxide. 
Put  the  mixture  in  a  large  test  tube  or  small  flask.  Close  the  container 
with  a  stopper  through  which  a  small  delivery  tube  passes.  Fix  the  con- 
tainer in  a  slanting  position  on  an  iron  stand,  and  run  the  free  end  of 
the  delivery  tube  into  a  tray  of  water.  Heat  the  mixture  gently  with  gas 
or  alcohol  flame.  Fill  several  bottles  with  water;  invert  one  over  the 
mouth    of   the    delivery   tube    in    such    a    manner    that    the    water    will    be 

*  The  stem  should  be  held  in  the  liquid  during  the  cutting  so  that 
the  cut  surface  is  not  exposed  to  the  air. 


120  PLANT  FOODS  AND  PLANT  GROWTH 

forced  out  by  the  gas.  When  all  the  water  has  been  forcod  out,  cover  the 
mouth  of  tlie  bottle  with  a  card  and  invert.  Repeat  until  three  or  four 
bottles  are  filled. 

This  gas  is  oxygen.  Note  its  color.  Thrust  glowing  pieces  of  char- 
coal into  the  bottles  and  note  the  result.     Explain. 

11.  Study  of  Carbon  Dioxide. — Put  some  small  fragments  of  marble 
into  a  flask  thoroughly  closed  with  a  cork  through  which  has  been  passed 
a  delivery  tube  as  in;  Exercise  10,  and  a  small  funnel  or  thistle  tube.  Pour 
dilute  hydrochloric  acid  into  the  funnel  until  the  lower  end  is  covered. 
Collect  the  resulting  gas  (carlwn  dioxide)  as  in  Exercise  10.  Run  a 
little  of  the  gas  into  lime  water  and  note  the  result.  Take  a  little  fresh 
lime  water  and  blow  into  it  through  a  straw  or  tube.  Note  the  result. 
Explain. 

12.  Burn  a  piece  of  charcoal  in  a  l)ottle  of  pure  oxygen.  Remove 
quickly,   pour   in   lime  water  and   shake.     Note   the  result.     Explain. 

13.  Study  of  Hydrogen. — Put  a  few  fragments  of  zinc  into  the 
same  or  a  similar  apparatus  as  used  in  Exercise  10.  Add  the  dilute 
hydrochloric  acid  but  allow  the  gas  to  be  given  ofl'  for  some  minutes.  Then 
collect  a  bottle  of  the  gas  (hydrogen)  and  place  upside  down  on  a  table. 
Darken  the  room  and  thrust  a  burning  match  into  the  inverted  bottle. 
Note  the  result. 

14.  Study  of  Nitrogen. — Fasten  a  bit  of  candle  to  a  cork  and  float 
in  a  vessel  of  lime  water.  Light  the  candle  and  cover  with  a  wide  bottle 
so  placed  that  the  edges  are  under  water.  When  the  candle  goes  out, 
cover  the  mouth  of  the  bottle  with  card-board  or  cork  and  reverse  so  as  to 
retain  all  the  water  that  has  risen  in  tlie  l)ottle.  Shake  thoroughly,  and 
allow  to  stand  until  the  upper  part  is  clear.  What  has  been  used  by  the 
burning  candle?  What  gas  has  Ijeen  formed  as  indicated  by  the  lime  water 
in  the  bottle?     The  gas  remaining  in  the  bottle  is  nitrogen. 

QUESTIONS 
L  What  are  the  three  great  groups  of  substances  found  in  plants? 

2.  Of  what  elements  are  each  of  these  food  substances  composed? 

3.  What  are  the  sources  of  these  elements? 

4.  What  otlier  elements  are  found   in   plants? 

5.  What  relation  does  the  texture  of  the  soil  bear  to  the  water  con- 


tent? 


6.  What   do   you   understand   by   humus? 

7.  What  do  you  understand  by  turgor? 

8.  What  do  you  understand  by  osmosis? 

9.  Why  do  plants  wilt? 

10.  What  do  you  understand  by  transpiration? 

11.  What  do  you  understand  by  piiotosynthesis? 


CHAPTER  XI 

THE  GYMNOSPERMS 

Thus  far  we  have  devoted  our  time  to  the  study  of  the 
higher  plants,  that  is  to  the  plants  v^hich  produce  flowers  and 
seeds.  This  great  group  of  trees,  shrubs  and  herbs  presents  by 
far  the  most  conspicuous  types  of  vegetation  and  includes  our 
most  important  agricultural  crops.  But  we  must  now  con- 
sider the  gijmnosperms  (for  classification,  see  Chapter  V),  that 
great  group  of  seed-bearing  plants  which  do  not  produce  true 
flowers.  They  are  also  called  coniferous  or  cone-bearing  plants 
because  of  the  cones  which  contain  the  seeds.  The  largest,  most 
important  and  best-knoAvn  gToup  is  the  order  Pinacece  which 
are  widely  distributed  throughout  the  world  especially  in  the 
northern  hemisphere.  They  are  the  pines,  spruces,  firs,  bal- 
sams, larches,  cypresses,  cedars,  hemlocks,  arbor  vitse  and  the 
giant  red  oaks  of  our  Pacific  coast. 

Structure  of  Stems. — The  general  character  and  gross  struc- 
ture of  the  stems  and  roots  is  somewhat  similar  to  the  angio- 
sperms,  but  the  leaves  are  modified  until  in  most  cases  they  are 
described  as  needles.  These  needles  may  be  compared  to  the 
midrib  of  an  ordinary  leaf,  but  when  cut  in  cross-section  and 
examined  under  the  microscope  they  show  a  thick  cuticle  and 
epidermis  covering  a  few  layers  of  sclerenchyma  cells  (Chapter 
VIII),  which  in  turn  cover  the  chlorophyll  bearing  parenchyma 
(Chapter  VIII).  The  small  size  and  peculiar  structure  of  the 
leaves  make  them  especially  well  suited  for  withstanding  either 
dry  or  cold  climates.  Most  coniferous  trees  shed  their  needles 
gi\^dually  and,  therefore,  are  in  foliage  the  entire  year.  For 
this  reason  they  are  known  as  evergreens  and  are  especially  suit- 
able for  ornamental  plantings.     Some  few  conifers  such  as  the 

121 


122  THE  GYMNOSPERMS 

bald  cypress  and  larch  are  deciduous,  i.e.,  shed  their  entire 
foliage  each  year  and  are  bare  during  the  winter  season. 

A  cross-section  of  the  stem  will  show  the  annular  rings  and 
medullary  rays  the  same  as  in  dicotyledonous  plants.  Very  thin 
sections  should  be  made  and  mounted  in  water  for  study  under 
the  microscope.  Each  section  is  cut  at  right  angles  to  the  other 
two  as  follows : 

(a)  The  cross-section  which  will  show  the  varying  thick- 
nesses of  the  cell-walls  by  which  the  annular  rings  are  produced, 
the  large  thin-walled  cells  of  the  late  summer  growth.  It  will 
also  show  the  medullary  rays  and  large  resin  ducts.  (&)  The 
radial  section  which  is  cut  longitudinally  and  on  a  plane  passing 
through  the  axis  of  the  tree  {i.e.,  quarter  sawed)  will  show  the 
peculiar  markings  of  the  cells  (tracheids).  By  studying  care- 
fully made  tangential  sections  which  are  also  longitudinal  but 
at  right  angles  to  the  radial  section  we  can  get  some  idea  of  these 
peculiar  markings. 

The  cones  are  of  two  kinds,  staminate  and  pistillate.  They 
correspond  to  bunches  of  staminate  and  pistillate  flowers.  We 
are  most  familiar  with  the  pistillate  (or  carpellate)  (Fig,  82,  c) 
cones  and  will  give  them  first  consideration.  They  become  the 
mature  cones  which  we  find  hanging  on  the  trees.  These  cones 
are  made  up  of  scales,  corresponding  to  needles  or  leaves,  but 
instead  of  being  arranged  in  circles  as  in  the  case  of  a  true 
flower,  they  are  arranged  in  spirals.  You  will  also  note  that 
when  they  spread  apart  they  each  bear  two  mnged  seeds. 

But  let  us  examine  an  immature  cone  such  as  we  will  find 
early  in  the  spring.  (Fig.  82,  c.)  Each  cone  is  small  and  the 
scales  naturally  spread  so  as  to  expose  two  ovules  (macrosporan- 
gia) .  (Fig.  82,  d. )  This  is  quite  different  from  the  true  flower- 
ing plants  in  which  the  ovules  are  always  enclosed  in  an  ovary. 

Pollination.— Tn  the  spring  we  will  also  find  clusters  of 
very  small  staminate  cones.     (Fie;.  82,  a.)     Each  scale  of  these 


POLLINATION 


123 


small  cones  is  a  stamen  (sporophyll)  bearing  sacs  (microspor- 
angia)  filled  with  great  quantities  of  yellow  pollen  grains 
{microspores)  which  fall  in  showers  and  are  scattered  by  the 
wind.  These  pollen  grains  are  provided  with  liattened  exten- 
sions of  the  cell-wall,  forming  wings  for  their  ready  support  in 
the  air. 


t<56 


FiQ.  82. — a,  cluster  of  staminate  cones;  b,  pollen  grain;  c,  pistillate  cone;  d,  scale  from 
pistillate  cone  showing  two  ovules. 


Some  of  the  pollen  is  canght  in  the  pistillate  cones  and  falls 
upon  the  exposed  ovules.  The  scales  close  and  the  pollen  grain 
produces  a  delicate  tube  which  penetrates  the  ovule,  reaches  the 
egg  and  results  in  fertilization  similar  to  that  described  for  the 
angiosperm.  (Chapter  VI.)  This  process  cannot  be  followed 
except  by  the  study  of  carefully  prepared  slides  with  the  aid 
of  the  microscope.  However,  the  interval  of  time  between  pol- 
lination and  the  maturity  of  the  seed  is  much  greater  than  in 
most  angiosperms.  The  seed  cone  enlarges  rapidly,  but  tlie 
seeds  are  not  mature  until  late  in  the  summer  of  the  following- 
year. 


124  THE  GYMNOSPERMS 

Cycadales. — Another  very  interesting  group  of  the  gtjmno- 
sperms  is  the  order  Cycadales  which  is  mostly  tropical  in  habit. 
In  this  order  we  find  the  Cycas  revoluta  which  is  frequently 
grown  in  greenhouses.  Its  chief  point  of  interest  botanically  is 
in  the  fact  that  it  possesses  many  characters  in  common  with  the 
ferns  and  forms  a  sort  of  connecting  link  between  the  Gymno- 
sperms  and  the  Pteridophytes  or  ferns. 

We  all  readily  recognize  the  great  value  of  the  Gymno- 
sperms.  Many  of  them  are  among  our  most  important  forest 
trees  from  which  we  derive  enormous  amounts  of  lumber  for 
building  purposes  and  cabinet  making.  They  also  furnish  our 
commercial  supply  of  turpentine,  resin  and  balsams.  The 
cypress  is  used  extensively  for  telegraph  and  telephone  poles. 
The  use  of  evergreens  for  ornamental  plants  is  directly  con- 
nected with  the  nursery  business  and  landscape  gardening  and 
involves  very  large  expenditures  of  money. 

EXERCISES    WITH    GYMNOSPERMS 

1.  Examine  a  number  of  evergreen  trees  and  note  their  straight 
shaft,  mode  of  branching  and  general  form. 

2.  Growtli  and  Leaves  of  Pines. — Examine  a  pine  tree  and  note 
the  long  shoots  that  are  produced  each  year.  Also  note  the  short  shoots 
composed  of  clusters  of  needles.  Count  the  needles  in  the  clusters  in  the 
different  kinds  of  pines  that  may  he  available.  Is  the  number  constant 
for  each  species? 

3.  Examine  a  needle  carefully;  make  crosshsections  by  cutting  the 
needle  in  a  bit  of  pith  and  examine  under  the  microscope.  Note  the  thick 
cuticle,  the  thick  epidermis,  the  sclerenchyma  and  the  chlorophyll-l)earing 
parenchyma. 

4.  Twigs  of  Cone-bearing  Trees. — Cut  across  radial  and  tangential 
sections  of  a  brancli  from  a  cone-bearing  tree  and  examine  under  the 
compound  microscope  and  note  the  points  referred  to  in  the  text. 

5.  Cone  Flowers. — Examine  young  staminate  and  pistillate  cones 
and  note  the  points  referred  to  in  the  text.  (This  material  can  be  col- 
lected in  the  spring  and  preserved  in  alcohol  or  formalin.) 

G.  Pollen  Grains. — Examine  some  of  the  pollen  grains  under  the 
compound   microscope. 


QUESTIONS  125 

7.  Seeds  and  Cone. — ■Examine  a  mature  cone.     Remove  some  of  the 
and   examine. 

8.  Study  Seedlings. — Plant  some  of  the  seeds  and  note  eliaraeters  of 
the  seedlings. 

9.  Greenhouse  Gymnosperms. — Visit  the  greenhouse  and  ask  to 
see    a    Cycas    revoluta. 

QUESTIONS 

1.  What  do  you  understand  by  Gymnofiperms:^ 

2.  Compare  the  leaf  of  iii  Gymnosperm  with  that  of  an  Angiosperm. 

3.  What  do  you  understand  by  deciduous? 

4.  Are  any  of  the  Gymnosperms  deciduous? 

5.  Have  you  seen  any  of  these  in  tlie  winter  condition? 

(i.  Name  the  parts  of  the  staniinate  and  pistillate  cones  of  a  con- 
iferous  tree. 

7.  Compare  these  parts  with  the  corresponding  parts  of  a  true  llovv- 
ering  plant. 


CHAPTER  XII 

ECOLOGICAL   RELATIONS 

The  growth  of  the  phiiit  is  influeiiced  by  many  factors, 
among  the  most  important  of  which  are  water,  soil,  temperature 
and  light.  The  combination  of  these  four  factors  may  not  be 
such  as  to  give  the  maximum  in  growth  and  productiveness; 
for  while  one  or  two  of  these  factors  may  be  in  the  correct  pro- 
portion for  the  best  growth  of  the  plant,  the  other  two  may  be 
in  proportion  unsuited  for  the  greatest  possible  development. 
The  plant  is  also  influenced  by  animals,  wind  currents,  and 
many  other  factors  too  numerous  for  discussion  at  this  time. 
When  a  factor  is  such  as  to  kill  or  prevent  the  growth  of  the 
plants  of  any  particular  species,  it  becomes  a  limiting  factor 
in  the  spread  of  the  species  regardless  of  the  character  of  the 
other  factors.  Lack  of  water  may  prevent  the  spread  of  a 
species  into  a  territory  when  all  other  factors  may  be  satisfac- 
tory. This  is  well  illustrated  by  the  great  desert  regions  of  the 
world  which  produce  abundant  vegetation  when  subjected  to 
irrigation.  Any  species  of  plants  will  extend  its  range  as  fast 
as  the  controlling  factors  will  permit,  and  will  reach  its  max- 
imum development  where  the  combination  of  the  factors  is  best 
suited  to  its  existence  and  its  minimum  where  it  is  most 
unsuitable. 

Water. — We  have  already  learned  that  plants  cannot  live 
without  water  and  that  it  is  the  most  abundant  compound  in  most 
plants  and  also  one  of  the  most  important.  It  passes  into  the 
plant  by  means  of  the  root-hairs  and  passes  out  of  the  plant  by 
transpiration,  mostly  through  the  leaves.  We  have  also  learned 
that  many  plants  are  composed  almost  entirely  of  water.  How- 
ever, plants  differ  in  the  amount  of  water  required  for  their 
126 


THE  HYDROPHYTE  SOCIETIES 


127 


existence.  Some  plants  float  in  the  water  and  have  no  direct 
connection  with  the  soil ;  others  are  rooted  to  the  soil  but  float 
in  the  water  (water  lilies).  Some  are  rooted  in  the  mud  but 
extend  fan  above  the  water  (cat-tails) ;  some  grow  in  wet  soil; 
still  others  grow  in  dry  soil  and  are  easily  killed  by  too  much 


Fig.  83. — Zone  formation  of  vegetation  dependent  upon  depth  of  water. 

water.     These  facts  enable  us  to  group  plants  into  societies  de- 
pendent upon  their  water  requirements.  (Figs.  83  and  84.) 

The  Hydrophyte  societies  are  made  up  of  those  plants  which 
live  in  the  water  or  in  very  wet  swampy  soils.  Ponds  and  lakes 
in  which  the  water  varies  in  depth  frequently  show  many  of 
these  societies  to  an  advantage ;  the  floating  plants  in  the  moder- 
ately deep  water,  the  cat-tails  near  the  margin  and  the  willows 
on  the  margin.  Rice  is  one  of  the  few  hydrophytes  which  is  of 
great  agricultural  importance. 


128 


ECOLOGICAL  RELATIONS 


The  Mesophyte  societies  are  those  made  up  of  plants  which 
require  a  fair  amouut  of  rainfall.  The  forest  and  prairie 
plants  and  most  of  our  agricultural  plants  are  mesophytes. 

The  Xerophyte  societies  require  very  little  water  and  in- 
clude the  desert  plants. 


Fig.  84. — Zone  formation  of  vegetation  dependent  upon  depth  of  water. 


In  addition  to  these  societies  we  have  also 

The  Halophytes  or  those  plants  which  grow  in  salt  water 
and  salt  marshes,  and 

The  Tropophytes  which  are  mesophytic  in  habit  for  a  part 
of  the  year  and  xerophytic  in  habit  for  the  remainder. 

Soil. — The  majority  of  plants  with  which  we  are  familiar 
grow  in  the  soil,  but  we  must  not  forget  that  a  great  number  of 


NITROGEN   OBTAINED   FROM  THE  AIR  129 

species  of  plants  live  in  the  water,  while  others  live  either  para- 
siticallj  or  saprophytically  on  plants  and  animals.  The  soil  in 
which  plants  live  must  have  a  suitable  texture  and  must  fur- 
nish certain  elements  which  constitute  most  of  the  crude  food 
materials  of  the  plants.  Since  our  agricultural  crop  plants  are 
dependent  upon  the  soil  and  since  the  animals  are  dependent 
upon  the  plants,  it  is  evident  that  all  animal  life  is  dependent 
upon  the  soil.  If  we  are  to  understand  plant  growth  we  must 
know  something  about  the  soil  in  which  the  plants  grow. 

The  various  soils  are  made  up  of  numerous  small  particles 
of  disintegrated  rocks  of  various  kinds,  in  which  is  usually 
mixed  more  or  less  decaying  or  decayed  organic  materials.  The 
disintegration  of  the  rocks  is,  due  to  the  freezing  of  the  water 
which  penetrates  the  minute  crevices,  to  the  grinding  action  of 
moving  masses  of  ice,  to  tlie  mechanical  and  solvent  action  of 
water  and  to  many  other  minor  influences.  Soils  are  designated 
as  gravel,  sand,  sandy  loam,  loam,  clay,  etc.,  dependent  upon  the 
coarseness  or  the  fineness  of  the  particles  of  which  they  are  com- 
posed. The  variation  in  the  texture  of  the  soil  results  in  varia- 
tion in  its  power  to  retain  water. 

The  most  important  elements  in  the  soil  which  either  serve 
as  food  or  influence  the  growth  of  plants  are  phosphorus,  potas- 
sium, calcium,  magnesium,  sulfur,  iron,  sodium,  chlorine,  sili- 
con, manganese,  aluminum  and  nitrogen.  All  of  these  except  the 
last  can  be  found  in  the  ash  of  the  plant  and  of  course  must  have 
been  taken  from  the  soil  by  the  plant.  These  elements  may  be 
in  the  soil  in  proportions  too  great  or  too  small  for  the  needs  of 
certain  plants  and  satisfactory  for  others,  or  may  be  present, 
but  in  such  a  form  as  to  be  unavailable  for  the  plant.  Since  the 
difl"erent  species  of  plants  are  unlike  in  their  requirements  we 
find  them  more  or  less  in  groups  dependent  to  some  extent  upon 
the  character  of  the  soil  in  which  they  grow. 

Nitrogen  Obtained  from  the  Air. — Probably  the  most  im- 


130  ECOLOGICAL  RELATIONS 

portant  of  all  the  elements  is  the  nitrogen  which  is  essential  for 
all  plants  and  animals.  Nitrogen  is  very  abnndant  in  the  air, 
but  the  plants  cannot  make  use  of  it  in  this  free  form.  However, 
the  air  penetrates  the  soil  and  its  nitrogen  is  seized  upon  by 
certain  bacteria  and  fungi  and  fixed  in  the  form  of  nitrates  which 
can  be  used  by  the  plants.  (Chapter  X.)  This  gives  us  one 
good  reason  for  keeping  the  soil  in  which  we  are  growing  plants 
in  loose  condition.  Nitrogen  is  also  carried  down  and  into  the 
soil  by  rainfall.  The  bacteria  found  in  the  tubercles  of  the 
leguminous  plants  are  the  most  important  organisms  in  this 
work.  Nitrogen  is  also  obtained  from  decaying  organic  mater- 
ials and  thi^  is  one  reason  that  humus  is  so  important  in  agri- 
cultural lands. 

Use  of  Fertilizers. — If  the  soil  does  not  contain  these  food 
elements  in  the  proper  proportions  or  if  any  of  them  are  unavail- 
able, the  farmer  endeavors  to  overcome  its  deficiencies  by  the 
application  of  fertilizers,  such  as  stable  manure,  bone  meal,  ni- 
trate of  soda,  rock  phosphate,  potash,  lime,  etc.,  or  by  the  grow- 
ing of  the  leguminous  plants  or  by  both.  In  order  to  do  this  to 
the  best  advantage  it  is  important  that  he  understand  the  crop 
plants  to  be  grown  and  their  food  requirements.  The  elements 
most  likely  to  be  lacking  in  farm  soils  are  nitrogen  (N),  phos- 
phorus (P),  potash  (K),  and  sometimes  calcium  (Ca). 

Temperature. — This  is  another  factor  of  plant  growth  which 
we  very  readily  recognize  and  we  know  that  certain  fruits  such 
as  oranges  and  bananas  grow  only  in  tropical  and  subtropical 
countries,  and  that  many  other  plants  are  limited  in  their 
range  by  the  temperature.  In  traveling  across  the  country  we 
easily  see  that  forest  and  prairie  sections  can  be  readily  divided 
into  smaller  areas,  such  as  the  pine  forest,  oak  forest,  beech 
forest,  etc.  We  also  recognize  great  belts  or  areas  of  agricultural 
crops,  such  as  the  corn  belt,  cotton  belt,  wheat  belt^  peach  belt, 
etc.     On  the  boundaries  of  these  belts  we  frequently  find  these 


PLANT  GEOGRAPHY  131 

crops  grown  with  considerable  difficulty  owing  to  droughts,  frosts 
and  other  factors. 

Light. — This  is  also  an  important  factor  which  is  very 
generally  recognized.  Our  attention  has  been  called  to  the 
fact  that  plants  turn  to  the  light  and  that  their  foliage  is  ad- 
justed to  receive  the  light  to  the  best  advantage.  (Chapter  IV.) 
But  a  little  careful  observation  will  show  us  that  while  some 
plants  thrive  best  in  the  direct  rays  of  the  sun  others  are  always 
found  growing  in  the  shady  places.  It  is  now  well  known  that 
some  of  our  agricultural  crops  thrive  much  better  in  the  shade 
than  in  the  open.  Coffee  is  very  generally  grown  in  the  shade 
of  larger  trees  and  many  plants  are  grown  in  an  artificial  shade 
produced  by  slat  coverings  or  by  large  cheesecloth  tents. 

These  and  many  other  factors  of  nature  which  influence  the 
spread  of  plants  have  given  rise  to  that  phase  of  botany  known 
as  Plant  Geogi'aphy. 

PLANT  GEOGRAPHY 

Plant  geography  is  so  closely  associated  with  Ecology  that 
it  is  practically  impossible  to  separate  the  two  subjects  by  well- 
defined  boundaries.  In  our  early  study  of  geography  we  learned 
that  the  earth  was  divided  into  five  zones :  Arctic,  Worth  Tem- 
perate, Torrid,  South  Temperate  and  Antarctic,  and  we  soon 
learned  to  associate  these  zones  with  cold,  temperate  and  hot 
climates.  But  a  little  later  we  learned  that  countries  in  the 
same  parallels  of  latitudes  did  not  necessarily  have  the  same 
temperature ;  mountainous  regions  in  the  torrid  zone  might 
be  cold  as  Iceland ;  the  Gulf  current  makes  England  much 
warmer  than  points  on  our  Atlantic  coast  which  are  much  farther 
south.  It  is  very  evident  that  elevations,  moimtains  and  water 
barriers  and  the  ocean  currents  exert  very  pronounced  influences 
on  the  temperature  of  a  country  and  its  plant  growth. 


132  ECOLOGICAL  RELATIONS 

A  little  later  we  learned  that  rainfall  was  fnlly  as  important 
as  a  climatic  factor  as  temperature  and  that  it  had  fully  as 
much  influence  on  the  character  of  the  vegetation.  Probably  the 
greatest  rainfall  in  the  United  States  is  over  a  small  area  of 
Gulf  coast  extending  from  w^estern  Florida  to  a  short  distance 
west  of  Xew  Orleans,  a  section  of  the  country  well  adapted  to 
growing  rice  and  sugar  cane.  The  rainfall  of  most  of  the 
southern  states  is  somewhat  higher  than  for  the  states  north  of 
the  Ohio  River,  but  cotton  has  reached  its  northern  boundary  far 
south  of  the  river.  The  rainfall  of  the  Rocky  Mountain  Plateau 
is  lower  than  for  any  other  part  of  the  United  States,  giving 
us  a  great  area  of  country  frequently  referred  to  as  the  American 
desert. 

EXERCISES  ON  PLANT  RELATIONS  TO  SURROUNDINGS 

1.  Moisture  and  Germination. — -Fill  two  small  flower  pots  with 
soil  of  tlie  same  kind,  put  into  an  oven  until  thoroughly  dry,  allow  to 
cool,  plant  seeds  in  botli,  add  a  definite  amount  of  water  to  one  from  time 
to  time,  keep  the  other  dry,  and  keep  both  in  a  warm,  well-lighted  place. 
Note  the  germination  and  growth. 

2.  Growth  in  DifTerent  Soils. — Fill  several  small  flower  pots  with 
different  kinds  of  soils  and  sand,  plant  with  seeds  of  the  same  kind,  give 
the  same  amount  of  water  to  each  at  definite  intervals,  keep  in  a  warm, 
well-liglitod  place.     Note  time  of  germination  and  rate  of  growth. 

o.  Influence  of  Sand  on  Rate  of  Growth.— Take  a  supply  of  rich, 
loamy  soil  and  a  supply  of  clean  sand,  fill  one  flower  pot  with  the  soil, 
a  second  with  three  parts  soil  plus  one  part  sand,  a  third  witli  two  parts 
soil  and  tAvo  parts  sand,  a  fourth  with  one  part  soil  plus  three  parts 
sand  and  a  fifth  with  pure  sand.  Plant  the  same  kind  of  seeds  in  all, 
give  the  same  amount  of  water  from  time  to  time,  and  keep  in  a  warm, 
well-lighted  placp.     Note  the  time  of  germination  and  rate  of  growth. 

4.  Temperature  Affects  Growth.— Fill  two  pots  with  the  same  kind 
of  good,  rich  soil  and  plant  with  same  kind  of  seeds.  Give  the  same 
amount  of  water  and  keep  each  in  a  well-liglitod  place,  but  keep  one  in 
a  warm  place  (70  degrees  F.  or  more)  and  the  other  in  a  cold  place 
(af)out  40  degrees  F.  or  less).     Note  tlie  rate  of  growth. 

5.  Effect  of  Light  on  Germination  and  Growth.— Fill  two  flower 
pots  witli   the  s;inu-  kind  of  good,   ricli   soil,   i)huit  with  the  same  kind  of 


QUESTIONS  133 

seeds,  give  the  same  amount  of  water  from  time  to  time,  keep  in  a  warm 
room,  but  keep  one  in  the  light  and  one  in  the  dark  ( closet  or  box ) .  Note 
the  time  of  germination  and  rate  of  growth. 

QUESTIONS 

1.  Name   the  four   most  important   factors   in   plant  growth. 

2.  Tell  of  the  importance  of  water  in  plants. 

3.  What  are  the   hydropliytos?     Give  examples. 

4.  What  are  the  mesophytes?     Give  examples. 

5.  What  are  the  xerophytes?     Give  examples. 

6.  What  are  the  halophytes? 

7.  What  are  the  tropophytes? 

8.  How  may  plants  olitain  the  nitrogen  found  in  air? 

9.  What  elements   arc   likely   to  be   deficient   in   some  soils? 

10.  How  does  temperature  att'ect  growth  of  plants? 

11.  Tell  of  the  influence  of   light  on  plant  growth. 

12.  Make  a  list  of  plants  that  thrive  in  partial  shade. 

13.  Make  a  list  of  common  food  plants  and  tell  in  what  part  of   the 
United  States  or  of  the  world  they  are  grown. 

14.  Same    for    common   fibre   plants,      ^^'hy   are    thoy   not   grown    over 
wider   ranges   of   country? 

15.  What  are  some  of  the  geographic   influences  governing  the   plant 
life  of  a  region? 


CHAPTER  XIII 
FORESTRY 

The  study  of  forestry  is  a  branch  of  botany  that  has  attracted 
a  great  deal  of  attention  in  recent  years.  When  America  was 
explored  and  settled  by  white  men,  millions  of  acres  were  cov- 
ered with  virgin  forest.  The  land  was  more  valuable  for  culti- 
vation than  the  forest  was  for  any  use  that  the  settlers  could 
make  of  it.  Therefore,  enormous  quantities  of  these  wonder- 
ful forests  were  cut  and  burned  in  the  course  of  settlement. 
But  with  the  increasing  population  and  decreasing  forests,  lum- 
ber and  wood  became  more  and  more  valuable,  until  the  United 
States  Government  found  it  necessary  to  set  aside  large  areas 
of  land  as  forest  reserves.  These  conditions  naturally  led  to  the 
study  of  forestry,  a  subject  which  involves  the  planting  and 
care  of  forests  and  proper  protection  and  economic  handling  of 
our  natural  forest  products  and  the  planting  and  care  of  shade 
trees.  (Fig.  85.)  Many  woodland  areas  have  been  denuded 
which  are  of  little  or  no  value  for  other  crops.  (Fig.  86.)  The 
United  States  Government  and  the  various  state  governments 
employ  a  large  number  of  professional  foresters  for  this  work, 
and  many  cities  employ  foresters  to  attend  to  the  planting  and 
care  of  shade  trees.  Foresti-y  is  now  recognized  as  one  of  the 
most  important  studies  in  our  large  institutions  of  learning. 
The  principles  of  forestry  are  alsoi  practiced  on  many  individual 
farms  throughout  the  land. 

Although  we  cannot  take  a  course  of  forestry  in  connection 
with  this  brief  course  in  botany,  we  can  learn  something  of  the 
life  of  the  individual  trees  of  which  the  forest  is  composed  and 
some  general  principles  of  tree  growth. 
134 


TREE  CHARACTERISTICS 


135 


Tree  Characteristics. — Trees  are  not  only  the  largest  plants, 
but  they  are  extremely  complex  and  highly  developed.  How- 
ever, each  tree  mnst  arise  from  a  single  cell,  in  exactly  the  same 
manner  as  any  other  plant,  and  is  subject  to  exactly  the  same 
laws  of  plant  growth  as  any  other  plant.     A  tree  is  a  woody 


Fig.  85. — Modern  forestry  methods  provide  for  perpetual  crops  of  lumber  and  other 
forest  products.  Forest  beetles  are  held  in  check  by  burning  the  twigs  after  each  harvest. 
(U.  S.  D.  A.) 


plant  with  a  single  stem  or  trunk  which  may  be  straight  with 
many  side  branches  or  the  trunk  may  divide  into  subdivisions. 
It  has  a  well-developed  root  system  which  gives  it  firmness  and 
by  which  it  secures  water  and  mineral  foods.  It  has  leaves  of 
size,  shape  and  arrangement  peculiar  to  its  species.  The  flowers 
of  some  trees  are  large  and  showy  while  those  of  others  are  so 
small  and  inconspicuous  that  many  people  never  see  them  and 


136 


FORESTRY 


believe  that  certain  species  of  trees  never  produce  flowers.  The 
fruits  are  of  various  kinds  and  will  repay  you  for  careful  study. 
Trees  have  definite  forms  which  are  characteristic  of  their 
species ;  some  trees  are  low  with  round  dense  heads,  as  the  Nor- 
way maples,  others  are  tall  and  open  as  the  elm  and  plane-tree ; 
some  have  a  single  straight  shaft  as  the  pine  and  hickory,  while 
in  others  the  main  trnnk  branches  in  such  a  manner  as  to  lose 
its  identity  in  several  subordinate  branches. 


Fia.  86. — Denuded  of  forest  growth  by  ruthless  cutting  and  fires.  A  barren  rocky   waste 
ie   left,    unsuited    to    other    agricultural    crops.    (U.  S.  D.  A.) 

Tree  Foods. — The  tree  uses  the  same  kind  of  food  and 
secures  it  in  the  same  manner  as  any  other  plant  (Chapter  X), 
and  the  amount  of  energy  recjuired  in  securing  the  raw  food, 
transferring  it  throughout  the  plant,  and  making  it  into  ma- 
terial of  its  own  is  far  greater  than  we  can  appreciate.  Wood  is 
composed  primarily  of  carbon,  oxygen  and  hydrogen.  When 
absolutely  dry  about  one-half  its  weight  is  carbon.  We  have 
already  studied  the  processes  and  results  obtained  in  burning 
M'ood.     (Chapter  TX.) 


TREES  PRODUCE  GREAT   NUMBERS  OF  SEEDS  137 

Tree  Growths, — We  have  already  learned  something  of 
growth  (Chapter  X)  and  know  the  part  played  by  the  cam- 
hium.  When  we  think  of  the  growing  tree,  we  must  think  of 
the  thin  cambium  in  not  only  the  trunk  but  in  every  branch  and 
twig,  and  in  every  root  and  rootlet.  (Chapter  VI 11. )  When  an 
annular  ring  is  once  formed,  its  position  in  the  tree  is  never 
changed,  but  new  annular  rings  will  be  formed,  each  outside 
of  the  preceding  one.  In  most  trees  the  inner  wood  becomes 
darker  and  harder  with  age  and  is  known  as  the  heart-wood, 
while  the  outer  which  is  softer  and  lighter  in  color  is  known 
as  the  sap-wood.  The  passage  of  water  through  the  heart-wood 
is  checked,  but  it  continues  to  pass  through  the  sap-wood  during 
the  life  of  the  tree.  As  the  tree  grows,  the  amount  of  heart- 
wood  increases  by  continual  additions  from  the  cambium.  Tis- 
sues of  different  w^oods  have  peculiar  characters  by  which 
stiidents  can  readily  recognize  them. 

Conditions  of  Growth. — Diiferent  species  of  trees  require 
different  conditions  for  their  growth.  Some  grow  in  cold 
climates,  others  in  wrywl  climates ;  some  in  dry  soils,  and  others 
in  swamps  ;  some  require  certain  kinds  of  soil  and  light  exposure. 
Natural  forests  are  seldom  of  a  single  species  but  of  several 
species  which  live  and  grow  under  the  same  or  similar  condi- 
tions. Under  natural  conditions  there  is  a  continual  struggle 
between  the  trees  for  food,  water,  and  light,  and  many  trees 
die  because  other  trees  near  them  are  more  vigorous. 

Trees  produce  great  numbers  of  seeds,  but  very  few  of  these 
seeds  produce  trees.  M'any  of  them  fall  in  places  where  the 
soil,  water  or  light  requirements  are  unsuited  to  their  existence, 
or  are  destroyed  by  man  or  some  of  the  lower  animals.  How- 
ever, some  of  them  grow  where  they  fall  and  some  of  them  are 
carried  for  long  distances,  grow  and  may  be  the  beginning  of  a 
new  forest  area.  Some  young  trees  are  more  vigorous  than 
others  of  the  same  kind,  grow  faster,  overtop  tliom  and  shut 


138  FORESTRY 

oli"  the  light  and  eventually  starve  them  to  death.  A  few  are 
able  to  grow  beneath  the  shade  of  others.  [Sometimes  a  forest 
is  so  dense  that  it  is  difficult  for  young  trees  of  the  same  species 
as  the  forest  to  get  a  start,  but  other  trees  of  a  different  species 
and  with  different  light  requirements  may  become  established. 

Forest  Enemies. — The  forest  has  many  enemies ;  the  most 
destructive  is  man  who  may  lumber  it  with  gi-eat  waste,  or  use 
it  for  grazing  with  great  losses  to  the  young  growth,  or  care- 
lessly set  fires  by  which  large  areas  are  destroyed. 

Insects,  fungi,  wind  storms  and  snow  storms  also  take  heavy 
toll  from  these  natural  resources. 

EXERCISES  ON  FORESTRY 

1.  Learn  the  names  of  as  many  trees  as  possible  on  your  street,  in 
your  town,  in  the  park  or   in  a  near-by  forest  tract. 

2.  Collect  flowers,  seeds  and  leaves  of  as  many  trees  as  possible. 

•'5.  Forms  of  Trees. — ^lake  a  diagram  showing  the  peculiar  branch- 
ing  and    form   of   the   common   trees. 

4.  Tree  Differences. — Make  studies  in  the  woods  or  elsewhere  and 
report  on  what  kinds  of  trees  in  your  vicinity  are  the  tallest  and  what 
kinds  are  the  shortest,  what  ones  make  the  densest  shade,  what  ones  en- 
dure shade,  what  are  rapid  growers  and  what  are  slow  growers  ? 

5.  Study  blocks  of  different  kinds  of  wood  and  learn  to  recognize 
them.     Carpenters  and  other  wood  workers  can  help  you  in  this  study. 

0.  Close  and  Open  Plantings- — Compare  the  sliapes  of  trees  of  any 
species  in  dense  plantings  with  the  same  in  open  places.     Explain. 

QUESTIONS 

1.  What  useb  are  made  of  the  lumber  trees  in  your  community? 

2.  What  fruit  -  producing  trees  are  found  in  the  forests  of  your 
community? 

3.  What  nut-producing  trees  are  found  in  the  forests  of  your  com- 
munity ? 


CHAPTER  XIV 
PLANT  DISEASES 

Plants  are  subject  to  diseases  whicli  are  similar  in  cause 
and  character  to  those  of  the  animal,  except  that  the  majority  of 
animal  diseases  are  caused  by  bacteria,  while  the  majority  of 
plant  diseases  are  caused  by  fungi. 

A  healthy  plant  is  one  in  which  all  the  parts  are  perform- 
ing their  regular  functions ;  a  plant  which  is  growing  and  pro- 
ducing fruit  in  the  regular  manner.  A  disease  is  any  condition 
which  interferes  with  the  regular  functions  of  the  plant  or 
causes  its  death. 

Anything  that  interferes  with  the  taking  of  food  materials  of 
any  kind,  with  photosynthesis,  with  the  movements  of  plant 
fluids,  with  transpiration,  with  reproduction  or  with  any  other 
function  of  the  plant  is  the  cause  of  disease.  The  disease  itself 
is  frequently  designated  by  the  name  of  the  causal  organism. 

Two  Groups  of  Diseases. — Diseases  may  be  conveniently 
grouped  into  organic  and  environmental: 

Organic    (caused   by   organisms) 


Fungi 

Flowering  plants 

Mites 

Bacteria 

Insects 

Nematodes 

Slime  moulds 

Environmental    (caused  by  surrounding   influences) 
Soil  Temperature  Smoke 

Moisture  Gas  Chemical   (near  factories) 

Some  Symptoms  of  Disease. — A  disease  may  cause  (a)  dis- 
colo7"ation  of  the  foliage  or  other  parts  of  the  plant;  (&)  new  or 
excessive  growth  ;  (c)  wilting;  {d)  unnatural  sliedding  of  parts ; 

139 


140  PLANT  DISEASES 

(e)  foliage  spots;  (/)  perforation  of  foliage;  (g)  variegation 
of  foliage;  (h)  dying  of  leaves  and  twigs;  (i)  dwarfing  or 
atrophy  of  parts;  {j)  development  of  distorted  or  abnormal 
growths,  such  as  witches  broom,  galls,  corky  out-growths,  etc. ; 
(k)  cankers;  (Z)  increase  in  size  or  modification  of  parts;  (m) 
curling  of  foliage  and  formation  of  rosettes;  (ri)  hairy  roots; 
(o)  exudation  (gums,  resins)  ;  (/>)  sun  burns;  (q)  rot  of  fruits, 
stems  or  roots. 

The  most  noticeable  diseases  of  plants  are  the  rots  of  fruits 
and  stems  which  are  usually  caused  by  fungi  and  bacteria ; 
blights  of  the  leaves,  stems,  flowers  and  fruits,  which  are  also 
caused  by  bacteria  and  fungi ;  spots  on  leaves  and  fruits,  which 
are  caused  by  both  fungi  and  bacteria ;  mildeivs,  which  are  white 
powdery  fungous  growths  on  leaves,  twigs  and  fruits ;  smuts  and 
rusts,  which  are  fungous  diseases  of  grains  and  other  plants ; 
cankers,  which  may  be  due  to  fungi  or  other  causes ;  yellowings, 
mosaics,  and  other  discolorations,  which  may  be  due  to  any  one 
of  many  causes. 

Wilts, — When  the  disease  injures  or  destroys  the  root  sys- 
tem, the  food  and  water  supply  from  soil  is  reduced  or  cut  off 
and  the  plant  is  either  weakened  or  killed.  Diseases  of  the 
stem  may  have  the  same  effect.  Diseases  of  the  foliage  may 
interfere  with  the  absorption  of  carbon  dioxide,  the  transpira- 
tion of  water  and  the  photosynthesis  of  the  plant. 

The  wilt  diseases  are  usually  due  to  fungi  or  bacteria  which 
live  in  the  tracheary  tissue  of  the  fibro-vascular  bundles  and  thus 
interfere  with  the  rise  of  water.  These  diseases  are  especially 
injurious  on  herbaceous  plants.  The  fact  that  the  organisms  live 
within  the  plant  make  it  impossible  to  treat  by  means  of  spray- 
ing. Many  of  these  wilt  organisms  live  in  the  soil  from  year  to 
year  and  cannot  be  controlled  except  by  crop  rotatioii  in  which 
it  is  necessary  to  use  crops  which  are  not  subject  to  the  disease 
in  question. 


ROOT  DISEASES 


141 


Root  Diseases. — The  crown  gall  (Fig.  87)  is  one  of  the  very 
common  diseases  of  onr  fniit  and  other  trees,  roses,  berries  and 
many  other  plants.  It  is  cansed  by  bacteria  and  appears  as 
abnormal  c;rowths  on  the  roots  and  sometimes  on  the  trunk  and 


Fig.  87. — Young   tree   with   crown   gall. 


branches.  In  some  cases  it  does  bnt  little  harm,  but  in,  other 
cases  it  reduces  the  vitality  of  the  plants  and  in  extreme  cases 
causes  death.  The  so-called  hairy  root  of  the  apple,  pear  and 
quince  is  caused  by  the  same  organism.     The  roots  of  these  dis- 


142 


PLANT  DISEASES 


eased  trees  are  covered  with  numerous  small  roots  which  are 
usually  associated  with  small  galls.  There  is  no  known  treat- 
ment for  this  disease.     Diseased  trees  should  not  be  planted. 

Galls  or  knots  on  the  roots  of  plants  may  be  due  to  other 
causes.  Among  the  most  common  are  the  galls  on  the  roots  of 
apples  and  grapes  which  are  caused  by  insects ;  abnormal  growths 


Fig.  88. — Leaf  spot  disease  of  the  pear. 


on  the  roots  of  cabbage  and  related  plants  due  to  slime  moulds ; 
and  knots  on  many  plants  due  to  minute  worms  (nematodes). 
These  and  many  other  diseases  of  the  root  systems  of  plants  in- 
terfere with  nutrition,  dwarf  the  plants,  reduce  the  crop  and 
frequently  cause  death. 

The  leaf  diseases   are  mostly  due  to  fungi  which  cause  leaf 
spots,  leaf  curls,  blights,  wilting,  dying  and  droppings.     One  of 


THE  DISEASES  OF  THE  FRUITS  143 

the  most  noticeable  of  these  diseases  is  the  leaf  curl  of  the  peach 
which  is  a  fungous  disease  occurring  in  the  spring  and  causing 
the  leaves  to  curl,  turn  yellow  or  pinkish  and  finally  drop.  In 
severe  cases  practically  all  the  leaves  fall.  The  tree  puts  out 
new  foliage  but  drops  the  fruit.  The  disease  when  once  estab- 
lished persists  from  year  to  year.  It  can  be  controlled  by 
proper  spraying. 

The  many  leaf  spot  diseases  (Fig.  88)  reduce  the  amount 
of  leaf  surface  and  thus  reduce  the  amount  of  work  which  the 


'  Fig.  89. — One  of  the  apple  rots,  called  "bitter  rot." 

plant  is  capable  of  doing.     Therefore,  severe  leaf  injury  will 
usually  result  in  reduced  vitality  and  reduced  yield. 

The  diseases  of  the  trunks  of  trees  usually  start  with  wounds 
through  which  fungi  gain  entrance  and  cause  heart  rots.  Spe- 
cial care  should  be  taken  to  protect  street,  shade  and  ornamental 
trees  against  such  injury.  Tree  wounds  should  be  painted.  The 
filling  of  tree  cavities  is  very  satisfactory  if  well  done. 

The  diseases  of  the  fruits  may  appear  as  deformities,  spot- 
tings  and  rots.  (Figs.  89  and  00.)  The  great  majority  of  these 
diseases  are  due  to  fungi.  If  you  will  examine  the  rots  on  a 
number  of  apples  of  various  kinds  you  will  be  able  to  throw 


144 


PLANT  DISEASES 


them  into  several  groups.  These  diseases  are  especially  severe 
on  fleshy  fruits,  such  as  apples,  pears,  peaches,  plums,  cherries, 
tomatoes  and  many  other  plants.  Many  of  these  diseases  can 
be  held  in  check  by  the  proper  spray  treatment. 

The  diseases  of  the  grain  crops  are  very  destructive  and  are 
the  causes  of  heavy  losses.    The  most  conspicuous  and  most  im- 


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portant  of  these  diseases  are  the  rusts  and  smuts  (Fig.  91)  which 
are  fungous  growths  in  and  on  the  plants.  But  there  are  many 
other  less  prominent  diseases  of  the  grain  plants  which  are 
very  destructive. 

The  study  of  plant  diseases  is  a  study  in  itself,  a  well-defined 
branch  of  botany  known  as  Plant  Pathology.  Most  of  the  Agri- 
cultural Experiment  Stations,  of  which  there  is  at  least  one  in 
each  state,  employ  one  or  more  plant  pathologists  who  should  be 
consulted  by  the  growers  of  crops. 


THE  STUDY  OF  PLANT  DISEASES 


145 


10 


Fig.  91. — Smut  disease  of  oats.      Healthy  oats  at  ri>;lit. 


146  PLANT  DISEASES 

The  control  of  plant  diseases  depends  on  the  cause  and  char- 
acter of  the  disease  in  question.  In  some  cases  the  diseases  are 
carried  on  the  seed  and  can  be  controlled  by  seed  selection  and 
seed  treatment ;  some  diseases  are  carried  on  nursery  stock  which 
should  be  subjected  to  careful  insjDection  for  the  elimination  of 
both  diseases  and  insect  pests ;  some  diseases  persist  in  the  soil 
and  can  be  controlled  by  crop  rotation  and  soil  sterilization  ;  and 
other  diseases  are  controlled  by  spraying.  Advice  concerning 
the  character  and  treatment  of  diseases  of  plants  can  be  obtained 
by  writing  directly  to  the  Agricultural  Experiment  Station  of 
your  state. 

EXERCISES  WITH  PLANT  DISEASES. 

1.  Collections  Showing  Diseases.  —  Examine  a  large  number  of 
plants  and   make  oollcotions  of  diseased   plants  or  parts  of  plants. 

2.  Inoculating  Soiind  Apples. — Select  a  few  sound  apples,  wash 
in  5  per  cent  formaldehyde,  then  in  sterilized  water,  and  put  them  in 
two  or  more  closed  glass  dishes  that  have  been  treated  in  the  same 
manner.  Set  one  or  more  aside  for  comparison.  Puncture  the  apples  in 
the  other  with  a  sterilized  needle  or  sharp  pointed  knife  and  insert  a 
minute  fragment  of  the  rotten  part  of  another  apple.  Observe  from  day 
to    day   and    report   results. 

3.  Examine  apples  kept  in  this  manner  for  gigng  of  formation  of 
spores.  It  may  be  necessary  to  keep  them  under  observation  for  a  month 
or  more. 

4.  Potato  Diseases. — These  experiments  may  be  duplicated  with 
potatoes  and   other  plants. 

5.  Make  a  list  of  diseases  as  a  result  of  your  own  observation. 

QUESTIONS 

1.  What  do  you  understand  by  "plant  diseases"  ? 

2.  Enumerate  the  common  symptoms  of  disease. 

3.  To  what  causes   are  these  due? 

4.  Explain  a  common  cause  of  wilt. 

5.  Descrilje  the  crown  or  root  gall  and  its  effect. 

6.  What  are  the  chief  forms  of  leaf  diseases? 

7.  Name  some  common  plant  diseases  which  you  know. 


CHAPTER  XV 
PLANT  BREEDING 

This  verv  important  branch  of  botany  which  is  attracting 
so  much  attention  at  the  present  time  and  which  is  so  often 
referred  to  as  a  new  subject,  no  doubt  began  with  the  earliest 
dawn  of  civilization.  Man  selected  and  cultivated  the  plants 
best  suited  to  his  purpose  and  the  excellent  qualities  of  many 
of  our  economic  plants  are  no  doubt  largely  due  to  plant  selec- 
tions conducted  by  many  generations  who  did  not  fully  appre- 
ciate just  what  they  were  doing.  Plant  breeding  is  based  on  three 
laws  of  plant  growth:  variation,  mutation  and  hyhridization. 
(Fig.  02.) 

Variation  is  that  law  of  nature  which  leads  to  differences 
of  more  or  less  importance  among  plants  of  the  same  species. 
Many  thousands  of  plants  of  a  species  may  appear  to  be  the 
same,  but  a  close  examination  will  show  that  no  two  are  exactly 
the  same.  By  selecting  seed  from  the  individual  plants  which 
possess  the  desired  characters  through  a  number  of  generations 
it  is  frequently  possible  to  emphasize  these  important  charac- 
ters. In  the  beginning  of  the  sugar-beet  industry  in  America, 
the  plants  yielded  about  seven  per  cent  sugar,  but  by  careful 
selection  we  now  grow  crops  that  yield  double  this  amount. 
Many  of  our  most  important  varieties  of  fruits,  vegetables  and 
grains  are  the  results  of  more  or  less  careful  selection  through 
many  generations. 

Mutation  is  the  law  by  which  plants  produce  new  species 
with  well-defined  characters  in  a  single  generation.  The  per- 
centage of  new  species  is  very  small  and  yet  of  sufficient  im- 
portance to  be  of  considerable  value  in  agriculture.     The  study 

147 


148 


PLANT  BREEDING 


of  mutation  is  so  ne\v_  that  we  do  not  know  how  mnch  we  are 
indebted  to  it  for  valuable  economic  plants.  Some  of  our  valu- 
able plants  which  we  have  considered  the  results  of  selection 
niav  r(\i]ly  be  the  results  of  mutation. 

Hybridization  is  the  production  of  new  varieties  (hybrids) 
by  the  cross  fertilization  of  more  or  less  closely  related  species. 
This  process  no  doubt  occurs  to  some  extent  in  nature,  but  man 
has  taken  advantage  of  the  possibilities  of  this  method  of  secur- 
ing new  and  valuable  varieties  and  many  men  are  now  devoting 
their  time  to  this  very  important  line  of  work.     The  method  is 


Fig.  92. — In  croesing  different  varieties  of  wheat  the  stamens  are  removed  before  they 
shed  their  pollen.  Tlie  pistils  are  impregnated  with  pollen  brought  by  a  soft  brusti  troui 
another  variety.   The  head  is  then  covered  with  a  paper  bag  and  properly  labeled.    tU.S.D.A.) 

not  difficult  but  I'equires  care,  time  and  patience.  The  pollen 
can  be  readily  collected  in  a  watch  glass  or  other  small  receptacle 
and  then  applied  to  the  stigmas  of  the  flowers  of  the  other  plants 
with  a  delicate  camel's  hair  brnsh.  The  stamens  of  the  opening 
flowers  should  be  removed,  the  pollen  applied  to  the  stigma  and 
the  blossom  then  protected  against  accidental  pollination  from 
other  sources  by  covering  with  a  paper  bag.  (Frontispiece.) 
After  a  few  days  the  bag  can  be  removed  and  a  tag  fastened  to 
the  shoot.  In  growing  annual  plants,  the  results  of  cross  breed- 
ing can  be  determined  in  a  comparatively  short  time,  but  in  the 
cross-breeding  perennials  the  time  will  be  much  longer  unless 


QUESTIONS  149 

the  seedlings  are  gi'iifted  into  niatnre  trees  and  bronght  to  frnit 
in  a  short  time. 

Selection.- — Of  course,  it  will  be  readily  seen  that  in  breed- 
ing plants  that  will  not  hybridize  or  that  do  not  produce  seeds, 
we  must  depend  entirely  on  selection.  In  fact,  selection  was 
the  most  important  factor  in  plant  improvement  nntil  recent 
years  and  is  now  a  method  that  can  be  used  with  great  advan- 
tage. Most  farmers,  fruit  growers  and  gardeners  can  select  their 
best  plants  for  seed  purposes  with  great  advantage  to  themselves. 

EXERCISES  IN  POLLINATION 

1.  Removal  of  Stamens. — Select  several  flowers  of  tomato  or  other 
plants  just  ready  to  open.  Ivemove  the  stamen  and  cover  with  paper  bags. 
Examine   in  a   week  or  ten   days. 

2.  Artificial  Pollinating. — Select  another  lot  of  flowers,  remove  the 
stamens,  toucli  the  pistil  with  open  stamens  from  anotlier  flower  of  the 
same  kind.     Examine  in  a  Meek  or  ten  days. 

3.  Pollination  in  Greenhouses. — Visit  some  local  greenhouse  in 
which  the  tomatoes,  cucumbers  and  other  vegetables  are  grown  and  see 
how    pollination    is    managed. 

QUESTIONS 

1.  How   are   common   plants   pollinated? 

2.  ^Vhat  insects  are  important  in  pollinating  plants? 
.3.  ISIake  a  list  of  crops  pollinated  by  insects. 

4.  Make  a  list  of  crops  pollinated  by  wind. 


CHAPTER  XVI 
WEEDS 

It  has  been  said  that  a  "  weed  is  a  plant  growing  in  the 
wrong  place."  There  is  much  truth  in  this  statement  for  many 
well-known  plants  are  pests  or  valuable  products,  depending 
upon  their  location.  The  morning-glory  is  a  beautiful  orna- 
mental plant  in  the  home  grounds  but  a  pest  in  our  cultivated 
fields ;  and  mustard  is  a  useful  plant  which  becomes  a  pest  when 
the  farm  lands  are  thoroughly  infested  with  it. 

Many  of  our  valuable  cultivated  crops  were  at  one  time  wild 
plants  of  the  plains  and  forest  which  man  has  found  to  be  use- 
ful and  has  learned  to  cultivate  in  an  advantageous  manner. 
In  fact,  if  we  would  go  far  enough  back  in,  the  history  of  man- 
kind, back  to  the  time  when  man  was  uncivilized,  we  should  no 
doubt  find  that  all  plants  were  at  one  time  wild  or  unculti- 
vated. With  the  progress  of  the  human  race  man  has  learned 
to  cultivate  and  make  use  of  many  plants,  but  never  in  all  his- 
tory has  man  put  forth  so  much  effort  to  conquer  nature  and 
utilize  her  products  as  at  present.  Every  year  sees  plants  that 
we  have  in  the  past  looked  upon  as  weeds  brought  under  culti- 
vation and  every  year  our  government's  traveling  specialists 
are  collecting  both  cultivated  and  uncultivated  plants  from 
abroad,  many  of  them  from  the  remote  comers  of  the  earth,  and 
sending  them  to  America  to  be  tested  in  order  that  their  value 
as  farm  crops  can  be  determined. 

Weed  Defined. — A  weed  is  not  only  a  plant  growing  in  the 

wrong  place,  but  it  may  be  a  plant  which  we  have  not  yet  learned 

to  make  use  of,  or  one  which  we  have  not  learned  to  cultivate 

profitably.    However,  for  our  purpose,  a  weed  is  a  plant  which 

150 


NEW  WEEDS  INTRODUCED  151 

interferes  with  the  growing  of  the  crop  in  which  wc  are  inter- 
ested. It  may  be  a  vahuible  crop  if  grown  separately,  but 
wc  do  not  want  it  to  interfere  with  the  crop  under  cultivation. 
The  weed  may  be  an  excellent  crop  in  one  part  of  the  world  and 
a  pest  in  another  part.  The  value  of  the  plant  depends  upon 
the  use  we  can  make  of  it  and  the  ease  and  profit  with  which 
it  can  be  grown. 

How  Weeds  are  Injurious. — Weeds  are  injurious  for  many 
reasons.  (1)  They  take  a  certain  amount  of  the  food  and 
water  which  the  crop  plant  should  have  for  its  growth.  The 
farmer  cannot  afford  to  have  his  crop  plants  weakened  and  the 
amount  of  the  harvest  reduced,  by  the  weeds  and  he  cannot 
afford  to  buy  fertilizers  to  feed  useless  plants.  (2)  Weeds  may 
prove  injurious  to  the  crop  by  shading  and  if  too  numerous 
may  completely  choke  out  the  crop  plants.  (3)  The  weeds 
may  harbor  certain  insects  and  fungi  which  attack  the  crops. 
(4)  Thistles,  nettles,  and  other  thorny  or  prickly  plants  may 
interfere  with  using  the  growing  crop  for  pasture  or  interfere 
with  tillage.  (5)  Weeds  in  the  meadow  reduce  the  feed  value 
of  hay.  (6)  The  presence  of  weed  seeds  in  the  harvest  crop  may 
reduce  its  value.     (Figs.  93  and  94.) 

Weeds  Sometimes  Useful. — It  is  sometimes  said  that  weeds 
are  useful,  especially  on  unused  lands,  because  they  serve  as  a 
cover  and  prevent  the  escape  of  nitrogen  and  can  be  plowed 
under  and  thus  used  as  a  fertilizer.  This  is  an  old  idea  that  has 
come  to  us  from  the  time  when  the  land  was  rested  by  being- 
left  uncultivated  for  a  period  of  one  or  more  years.  But  we 
now  know  that  in  most  cases  it  is  much  better  to  use  a  good 
agricultural  cover  crop.  Rye,  certain  clovers,  vetches  and  other 
plants  are  much  more  valuable  than  a  miscellaneous  lot  of 
weeds. 

New  Weeds  Introduced. — Wlien  a  new  country  is  settled 
and  brought  under  cultivation  we  find  certain  native  weeds, 


152 


WEEDS 


Fig.  93. — Some  conniion  weeds.     Left  to  right:  Jimson,  ragweed,  lamb's  quarter,  joint- 
weed,  rough  pigweed. 


Flo.  94. — Some  eommon  grasses.   Left  to  right;   crabgrass,   two  barnyard  grasses,   tw6 
of  foxtail,  panicum,  fescue. 


PREVENT   INTRODUCTION 


153 


Fio.  95. — Crop  seeds:  1,  red  clover;  2,  alfalfa;  3,  alsike  clover;  4,  sweet  clover;  5,  timothy; 
6,  red  top;  7,  Kentucky  blue  grass;  S,  sU'eet  vernal  crass;  9,  annual  rye  grass;  10,  tall  meadow 
oat  grass;  11,  English  rye  grass;  12,  orchard  grass;  13,  broom  corn  millet;  14,  Hungarian 
millet;   15,  German  millet. 


154  WEEDS 

some  of  which  disappear  rather  rapidly,  while  others  appear  to 
thrive  as  a  result  of  cultivation,  and  are  a  continual  source  of 
annoyance.  But  the  number  of  different  kinds  of  weeds  will 
increase.  Man  will  naturally  introduce  the  grains,  grasses, 
clovers  and  vegetables  that  he  believes  can  be  grown  advantage- 
ously and  more  or  less  weed  seeds  will  be  introduced  with 
them.  Some  of  these  w^eeds  will  gTow  for  a  single  season  and 
die  while  others  will  persist  from  year  to  year.  Other  weed 
seeds  will  be  carried  with  nursery  stock  and  on  the  feet  and  in 
the  hair  of  live  stock,  in  bedding  for  live  stock,  in  feeds  and 
in  packing  materials  and  in  many  other  ways.  In  many  local- 
ities stable  manure  is  shipped  from  the  cities  to  the  farms  and 
since  the  animals  from  which  it  is  secured  may  have  been  fed 
on  imported  feeds  and  bedded  with  materials  brought  from  a 
considerable  distance  we  can  easily  understand  how  great  quan- 
tities of  weed  seeds  can  be  introduced. 

Fighting  Weeds. — Every  grower  of  farm  crops  must  make 
a  continuous  fight  against  weed  pests.  In  doing  this  there  are 
two  general  methods  to  follow:  (1)  Prevent  the  introduction  of 
the  weeds  not  already  present  on  the  farm,  and  (2)  the  destruc- 
tion of  those  that  are  present. 

Prevent  Introduction. — The  introduction  of  many  weed 
pests  can  be  prevented  by  using  nothing  but  clean  seeds.  Many 
seeds,  especially  clover  and  grass  seeds,  frequently  carry  many 
weed  seeds.  The  examination  of  an  ounce  or  more  of  such 
seed  will  frequently  reveal  the  presence  of  many  seeds  of  trou- 
blesome weeds.  Unfortunately,  the  seeds  of  some  plants  are  so 
similar  to  certain  clover  and  alfalfa  seeds  that  they  cannot 
be  detected  by  persons  unfamiliar  with  their  minor  character- 
istics. The  Federal  government  and  most  of  the  State  gov- 
ernments employ  seed  analysts  who  make  examination  of  sam- 
ples which  are  sent  to  them.  Home-grown  seed  should  be  just 
as  carefully  examined  as  seeds  that  are  purchased  on  the  mar- 
ket.    (Figs.  95  and  96.) 


Fig.  96.— Weed  seeds:  1,  Night-flowering  catchfly  (Silene  erectifolia) ;  2,  Sheep's  sorrel 
(Rumex  acetosella) ;  3,  Curled  dock  {Humcx  crispus);  4, Pennsylvania  sniartweed  (Polygonum 
pennsylvanicum);  5,  Lamb's  quarter  {Chenopodiuvi  album);  6,  Tumbling  pigweed  {Ama- 
ranthus  retroflexus) ;  7,  Peppergrass  (Lepidium  virginicum) ;  8,  Field  cress  (Lepidium  cam- 
pestre);  9,  Yellow  trefoil  (Medicago  lupulina);  10,  Evening  primrose  {Onagra  biennis);  11, 
Wild  carrot  (Daucus  carota);  12,  Rugel's  plantain  (Flantago  Rugelii);  13,  Huckhorn  (Flan- 
tayo  lanceolate);  14,  Ox-eye  daisy  {Chrysanthemum  leucatithemum) ;  15,  Canada  thistle  (CnicUs 
arvensis);  16,  Bull  thistle  (Cnicus  lanceolatus);  17,  Yarrow  {Achillea  millefolium);  18,  Dan- 
delion {Taraxacum  officinale);  A,  ventral  side;  B,  dorsal  side.  1,  Caryophyllacea?;  2-4, 
Polygnacese;  5,  Chenopodiacese;  6,  Amaranthacese;  7-8,  Cruciferae;  9,  Leguniinosae;  10, 
Anagracea;;  11,  Umbellifera;;   12-13,  Plantaginaceae;   14-18,   Compositse. 


156  WEEDS 

Straw  aud  similar  material  wliicli  has  been  used  for  pack- 
ing and  is  likely  to  contain  weed  seeds  should  be  burned  or 
rotted  in  compost  to  kill  seeds.  Stock  bedding  and  feeds,  should 
be  produced  on  the  farm  whenever  possible,  instead  of  pur- 
chased from  a  distance. 

Eradication.— The  fight  against  weeds  already  on  the  farm 
will  depend  upon  many  conditions.  Many  weeds  can  be  erad- 
icated by  sowing  a  crop  which  requires  close  cultivation ;  others 
by  the  use  of  smother  crops ;  others  by  the  repeated  sowing  of  a 
quick-growing  crop  which  can  be  pastured  with  sheep. 

The  success  of  these  and  other  treatments  will  depend  in 
some  measure  on  the  training  of  the  farmer.  It  will  be  readily 
seen  that  the  methods  used  against  aimuals,  biennials,  and  per- 
ennials must  necessarily  vary.  Therefore,  the  greater  the  famil- 
iarity with  the  life  history  of  the  pest,  the  gi-eater  are  the  possi- 
bilities for  success. 

Perennial  weeds  will  thrive  best  in  fields  where  they  are 
least  disturbed,  as  in  pastures  and  hayfields.  When  such  w^eeds 
are  gaining  too  strong  a  hold,  many  of  them  may  be  destroyed 
by  plowing  the  field  and  using  it  for  cultivated  crops  for  a  few 
years.  Potatoes,  corn,  and  other  summer  crops  may  be  used, 
but  they  should  be  well  cultivated. 

Annual  weeds  are  often  very  bad  in  grain  fields  or  in  corn 
and  other  cultivated  fields.  They  may  be  choked  to  some  extent 
by  sowing  the  field  very  densely  with  grass  for  hay  or  pasture. 

EXERCISES  RELATING  TO  WEEDS 

1.  Make  a  collection  of  the  noxious  weeds  of  your  neighborhood. 

2.  Corn-field  Weeds.  — ■  Which  ones  of  these  are  most  commonly 
found  in  cultivated  fields? 

3.  Pasture  Weeds. — ^lake  a  list  of  the  weeds  most  common  in  the 
pastures   of   tlie   vicinity. 

4.  In  Grain  Fields. — If  possible,  examine  a  field  of  wlieat  or  other 
small  grain,  either  while  the  grain  is  growing  or  after  it  is  cut.  Make 
lists  of  the  weeds  growing  in  the  grain  or  in  the  field  after  harvest. 


QUESTIONS  157 

5.  Examining  Seed  Samples. — Cct  samples  of  clover  seeds,  and  other 
small  seeds.  Examine  eacli  sample  for  (a)  weed  seeds;  (b)  dead  seeds; 
(c)  foreign  inert  matter  or  grit;  {d)  sound  seeds  true  to  the  variety;  (e) 
others  of  useful  varieties.  Count  the  number  in  each  of  these  five  classes 
and  then  determine  the  percentage  of  each. 

6.  Numbers  of  Weeds. — Search  the  fields,  fence  rows,  road  sides 
and  other  places  for  dense  growths  of  weeds.  Bend  a  wire  into  a  circle 
or  use  a  barrel  hoop  and  throw  it  over  the  densest  cluster  you  can 
find,  count  the  number  of  weeds  in  the  circle.  Determine  the  number  in 
a  square  foot  and  calculate  the  number  per  acre  (43,560  sq.  ft.).  Do 
likewise  for  several  diHerent  species  of  weeds. 

7.  Study  the  smothering  influence  of  weeds  found  growing  in  rows 
of  young  garden  crops,  corn,  etc. 

QUESTIONS 

1.  What  is  a  weed? 

2.  In  what  ways  are  weeds  injurious? 

3.  How   are  weeds   introduced   into  new  localities? 

4.  Have  you  seen  instances  of  these? 

5.  How   can   a   farmer   prevent   the   introduction   of   weeds? 

6.  How  may  perennial  weeds  be  most  easily  eradicated? 

7.  How  may  annual   weeds  be  eradicated? 


CHAPTER  XVII 
PTERIDOPHYTES 

We  have  studied  that  group  of  plants  and  the  subdivisions 
(the  seed-bearing  phmts)  which  you  may  consider  the  most 
important  and  we  have  learned  that  there  are  three  other  great 
groups.  (Chapter  V.)  Although  these  groups  furnish  us  com- 
paratively little  in  the  way  of  food,  clothing  and  building  ma- 
terials, yet  they  are  of  great  interest  and  of  considerable  value 
to  man.  To  the  botanist  they  are  esj^ecially  interesting  because 
we  cannot  get  a  thorough  knowledge  of  the  plant  kingdom  with- 
out studying  them.  They  are  of  value  to  all  of  us  because  many 
plants  belonging  to  these  groups  are  of  commercial  value.  There- 
fore, let  us  consider  the  next  highest  group,  the  Pteridophytes, 
which  includes  the  ferns  and  the  related  plants. 

True  Ferns. — The  largest  and  most  familiar  group  is  the 
order  Filicales  or  true  ferns.  (Fig.  97.)  These  plants  have 
true  roots,  stems  and  leaves,  but  the  structure  of  the  stems  is 
quite  diiferent  from  anything  we  have  studied.  The  stems  may 
be  short  and  erect  or  creeping,  underground  type  known  as 
rhizomes,  giving  rise  to  many  roots  and  to  the  masses  of  green 
foliage  with  which  we  are  familiar.  But  in  tropical  countries 
we  frequently  find  the  beautiful  tree  ferns  with  their  very  large 
trunks.  If  we  cut  a  cross-section  of  a  stem  and  examine  it  under 
a  compound  microscope  we  find  a  well-developed  fibro-vascular 
system  composed  of  practically  the  same  tissues  as  in  the  higher 
plants  but  arranged  quite  differently.  The  wood  cells  are  in 
the  centre  surrounded  by  the  bast  cells  which  are  in  turn  sur- 
rounded by  an  endodermis.  This  is  known  as  the  concentric 
arrangement.  These  bundles  are  weak  as  compared  with  bun- 
158 


FRUIT  DOTS 


159 


dies  of  the  spermatopliytes,  but  the  stem  is  streng-thened  by  the 
masses  of  schlereiichymti  tissue  which  can  be  readily  seen. 

The  leaves  or  fronds,  as  they  are  usually  called,  are  very 
similar  in  structure  to  the  leaves  of  the  Angiosperm.  In  fact, 
the  similarity  is  so  striking  that  it  is  not  necessary  to  describe 
it  at  this  time,  but  the  student  will  do  well  to  make  a  careful 
study  and  comparison  of  the  leaf  with  that  of  the  Angiosperm. 


Fiu.  97. — A  fern  glade. 

(Chapter  IV.)  However,  the  leaves  tend  to  unroll  in  a  ]>einiliar 
manner  (Fig.  98)  which  can  be  readily  seen  and  which  is  char- 
acteristic of  the  ferns. 

Fruit  Dots. — On  the  under  surfaces  of  many  of  the  older 
leaves  will  be  found  numerous  fruit  dots  or  sori  (singular  sorus). 
(Fig.  99  and  100.)  They  vary  greatly  in  size,  character  and 
arrangement  in  the  different  species  of  ferns  and  in  most  cases 
are  covered  with  a  delicate  membrane  known  as  the  indusium. 


160 


PTERIDOPHYTES 


(Fig.  100.)  These  dots  contain  niunerous  sporangia  (singular 
sporangium)  (Fig.  101),  which  are  filled  with  spores.  Each 
sporangium  is  supported  by  a  stalk  and  from  a  side  view  appears 
to  be  flat,  but  as  a  matter  of  fact  is  slightly  thicker  in  the  centre 
than  on  the  margin.  The  marginal  cells  are  highly  specialized 
and  are  of  two  kinds ;  the  thick-walled  cells  from  about  three- 
fourths  of  the  distance  and  the  thin-walled  cells  for  the  re- 
mainder of  the  distance.  When  the  spores  (Fig.  102)  are 
mature,  the  drying  out  of  the  sporangia  results  in  an  uneven 

Fig.  100. 


Fig.  101. 


Fig.  102. 


Fig.  98. — Young  fern  leaf  showing  method  of  unrolling.  V 

Fio.  99. — Part  of  fern  leaf  showing  sori  or  fruit  clusters. 

Fig.  100. — Part  of  fern   leaf  showing  sori   with   indusium. 

Fig.  101. — Sporangium     from     fern     sorus. 

Fig.  102. — Fern    spores    from    sporangium. 

tesnsion  of  the  two  kinds  of  cells,  a  bursting  of  the  sporangium 
and  a  scattering  of  the  spores. 

Two  Steps  in  Reproduction. — The  spores  germinate  and 
eventually  form  what  is  known  as  ihe  protlialUum.  (Fig.  103,  e.) 
In  most  ferns  this  prothallium  is  very  small  and  somewhat 
heartshaped.  It  is  composed  of  chlorophyll  bearing  paren- 
chyma cells  and  has  many  rhizoids  which  are  very  similar  to  the 
root-hairs  of  the  higher  plants.  They  penetrate  the  moist  soil 
from  which  they  derive  both  water  and  food  in  the  same  man- 
ner as  root-hairs.  On  the  under  surface  will  be  found  numerous 
small  bodies,  the  archegonia  (singular  archegonium)    and  the 


HORSE  TAILS  161 

antheridia  (singular  antheridmm).  In  some  ferns  they  are 
borne  on  the  same  prothalhis  while  on  others  they  are  borne 
on  different  prothallia. 

The  Archegonia  (Fig.  103,  V)  are  borne  near  the  notch  of 
the  prothallus,  and  somewhat  flask-shaped  with  the  base  imbed- 
ded in  the  tissues  and  the  neck  extending  downward  and  slightly 
curved.  An  examination  with  the  compound  microscope  shows  a 
large  egg  (ovum)  or  female)  cell  (Fig.  103,  c")  in  the  large  part 
and  a  row  of  canal  cells  in  the  neck.  These  canal  cells  become 
gelatinous  or  semi-fluid  in  character. 

The  Antheridia  (Fig.  103,  h')  are  spherical  and  produce 
great  numbers  of  minute,  unicellular,  spiral,  free  swimming 
Iwdies  known  as  sperms  or  male  cells.  (Fig.  103,  c'.)  The 
sperm  cells  swim  in  the  moisture  oil  the  surface  of  the  prothallia 
and  the  soil,  and  some  few  eventually  reach  the  archegonia,  enter 
the  canal  and  one  unites  with  each  ovum  or  egg  cell.  This  is 
known  as  fertilization.  It  corresponds  to  the  fertilization  of 
the  egg  in  tlie  embryo  sac  of  the  Angiospemi.  (Chapter  VI.) 
As  a  result  of  this  fertilization,  cell  division  occurs  and  the 
egg  grows  into  a  fully  developed  fern.  (Fig.  103,  e^  /.)  With  the 
development  of  the  fern,  the  prothallus,  upon  which  it  at  first 
feeds,  is  gradually  destroyed. 

Horse  Tails. — There  are  many  other  fern-like  plants  which 
we  will  find  quite  interesting  if  we  have  time  to  study  them. 
Among  the  most  common  are  the  horse-tails  or  scouring  rushes 
(Equisetum).  The  aerial  stems  are  derived  from  an  under- 
ground stem  and  may  be  branched  or  unbranched,  hollow  jointed, 
fluted  with  well-marked  longitudinal  ridges  and  furrows  and 
infiltrated  with  silica  which  makes  them  rough  and  rigid.  The 
branches  and  modified  leaves  are  always  in  whorls  and  at  the 
nodes.  At  each  node  the  stem  is  surrounded  with  membran- 
ous sheaths  which  correspond  to  the  leaves  of  higher  plants.  A 
cone-shaped  fruiting  structure  is  borne  at  the  apex  of  the  stem 
11 


162 


PTERIDOPHYTES 


and  is  composed  of  modified  leaves  or  Sporophylls,  bearing  small 
sacs  or  sporangia  containing  the  spores.  The  spores  have  four 
spiral  rings  which  straighten  out  when  dry  and  roll  up  when 
wet  and  thus  cause  the  spore  to  move  over  short  distances.     The 


Fig.  103. — Diagrammatic  representation  of  the  life  history  of  the  fern:  a,  prothallium; 
b',  antheridium;  b",  archegonium;  c',  sperm;  c",  ovum;  d,  oospore;  e,  prothallus  and  young  fern; 
f ,  mature  fern  showing  under-ground  stem,  root  and  leaf  bearing sori ;  g,  sporangium ;  h,  spores. 

life  history  of  the  horse  tail  is  practically  the  same  as  that  of 
the  true  fern. 

Other  Fern-like  Plants. — The  so-called  club  mosses  or 
ground  pines,  the  selaginellas  and  the  quillwort  are  groups  of 
small  plants  which  have  life  histories  very  similar  to  that  of  the 
true  ferns. 

The  greatest  value  of  the  ferns  at  the  present  time  lies  in 
their  great  beauty  for  decorations  of  various  kinds  and  we  must 


EXERCISES  WITH  PTERIDOPHYTES  163. 

not  forget  that  the  growing  of  ferns  is  an  industry  representing 
many  thousands  of  dollars.  In  past  ages  tlie  ferns  were  much 
more  ahundant  and  much  larger  than  at  the  present  time  and 
we  are  indebted  to  them,  to  some  extent,  for  the  enormous  beds 
of  coal  from  which  we  secure  most  of  our  supply  of  fuel.  ( Chap- 
ter^ IX  and  XVIII.) 

EXERCISES  WIT«  PTERIDOPHYTES 

1.  Examine  a  fern  carefully  and  note  its  roots,  stem,  leaves,  sori  and 
indusium. 

2.  Cut  cross-sections  of  the  stem  and  examine  under  a  compound 
microscope  and  note  the  points  referred  to  in  the  text.  Material  for  this 
purpose  can  be  preserved  in  alcohol  or  formaldehyde. 

3.  Study  the  leaf  in  the  same  manner  as  indicated  for  leaf  of  the 
Angiosperm.      (Chapter  IV.) 

4.  Remove  a  sorus,  crush  and  examine  under  the  compound  micros- 
cope.    Note  the  character  of  the  sporangia  as  referred  to  in  the  text. 

5.  Examine  a  prothallus  with  a  hand  lens  or  under  a  low  power 
of  tlie  compound  microscope.  Material  for  this  purpose  can  usually  be 
secured    from    a    neighboring   greenhouse. 

QUESTIONS 

1.  Where  do  you  find  the  stems  of  the  fern? 

2.  Compare  the  fern  stem  with  tlie  stems  of  a  flowering  plant. 

3.  Compare  the  leaf  of  a  fern  with  the  leaf  of  a  flowering  plant. 

4.  What  do  you  find  on  the  fern  leaf  not  found  on  the  ordinary  leaf? 
Reference. — Read  all  you  can  al)out  tlie  formation  of  coal-beds.     For 

such  information  see  a  good  encyclopedia  and  works  on  Geology. 


CHAPTER  XVIII 
BRYOPHYTES 

We  will  now  study  the  two  great,  groups  of  Bryopliyies,  the 
Musci  or  mosses  and  the  Hepaticce  or  liverworts.  They  are 
of  little  value  at  the  present  time  except  for  packing  material 
where  it  is  necessary  to  retain  moisture,  but  in  past  ages  (the 
Carboniferous  Age)  they  were  much  more  abundant  than  at 
any  time  since  and  we  are  indebted  to  them  for  the  greater  part 
of  our  enormous  beds  of  coal  which  we  are  now  using. 

Mosses, — An  ordinary  moss  plant  presents  an  upright  stem 
with  three  more  or  less  distinct  rows  of  leaves.  A  more  careful 
examination  will  show  us  that  this  stem  is  very  weak,  that  it  does 
not  contain  a  fibro-vascular  bundle  but  is  composed  of  elongated 
parenchyma  cells.  We  will  find  also  that  the  leaves  are  com- 
posed entirely  of  parenchyma  cells  and  that  their  apparent  mid- 
rib is  composed  of  elongated  cells.  These  characteristics  very 
readily  convince  us  that  we  are  studying  a  very  simple  type  of 
plant  as  compared  with  the  Pteridophytes  and  Spermatophytes. 

Arising  from  the  top  of  this  plant  is  a  long,  slender  stem, 
setea,  bearing  a  capsule  which  is  covered  with  a  cap  or  calyptra. 
(Fig.  104,  a,  h.)  If  we  remove  this  cap  we  will  find  the  oper- 
culum  (Fig.  104,  c),  which  is  a  small  cover  on  the  end  of  the 
capsule.  If  we  remove  the  operculum  (Fig.  104,  e)  we  will  find 
the  peristome  or  teeth  (Fig.  104,  c?.)  These  teeth  are  very  sensi- 
tive to  varj'ing  degrees  of  moisture  which  causes  them  to  move 
inward  and  outward  and  thus  controls  the  distribution  of  the 
spores  which  are  borne  within  the  capsule.  These  spores  will 
grow  and  each  produce  a  filamentous  prothallus  or  protonema 
which  gives  rise  to  new  moss  plants. 
164 


MOSSES 


165 


But  moss  plants  also  have  sexual  organs  similar  to  the  ferns. 
Thej  are  borne  in  the  tops  of  the  leafy  plants  early  in  the  spring 
and  are  known  as  antheridm  and  arcliegonia.  (Fig,  104,  f,  g.) 
The  antheridia  are  club-shaped  and  have  very  long  necks.     The 


Fig.  104. — a,  mature  moss  plant;  b,  capsule  covered  with  calyptra;  c,  capsule  without 
calyptra;  d,  capsule  with  operculum  removed  showing  peristome;  e,  operculum;  f,  arche- 
gonium;  g,  antheridium;  h,  paraphyses  or  sterile  organ. 

antheridia  and  archegonia  arc  always  borne  on  different  plants. 
The  process  of  fertilization  is  practically  the  same  as  -in  the 
ferns  and  the  fertilized  egg  grows  into  the  seteee  and  capsule 
referred  to  above. 


166 


BRYOPHYTES 


There  are  two  large  groups  of  mosses,  the  Bryales,  which 
we  have  just  described  and  the  Sphagnales.  This  hitter  group 
is  the  characteristic  moss  of  the  sphaguum  swamps  and  was  the 
most  important  group  of  phmts  in  the  formation  of  peat  and 
coal  beds. 

The  Hepaticae  or  liverworts  are  not  so  familiar  to  most 
of  us  as  are  the  mosses  and  ferns.  They  rank  next  below  the 
mosses  and  are  an  extremely  interesting  group  for  study,  but  of 
very  little,  if  any,  economic  value.  There  are  several  divisions 
of  the  hepaticae,  but  one  of  the  largest  and  most  common  forms 


nit 

Fig.  105 — Marchantia    polymorpha    showing    two    cupules    bearing    gemmule. 

Fig.  106. — Surface  view  of  marchantia  polymorpha  very  much  magnified. 

Fig.  107. — a,  female  plant  of  marchantia  polymorpha  bearing  two  archegonial  branches; 

b,  also  a  single  antheridial  branch  from  a  male  plant. 

is  known  as  Marchantia  polymorpha.  (Fig.  105.)  It  reminds 
us  of  the  fern  prothallus  but  is  much  larger  and  branching.  It 
is  thick  along  its  central  axis  and  thin  at  the  edges,  lies  flat  on 
the  wet  soil  and  has  many  rhizoids.  The  upper  surface  is 
divided  into  small  areas  with  a  small  opening  (stoma)  (Fig. 
106)  in  the  centre  of  each.  These  small  areas  give  it  a  super- 
ficial resemblance  to  the  liver  of  an  animal  and  therefore  the 
name  "  liverwort."  As  the  apical  part  of  the  plant  grows  the 
basal  part  is  gradually  dying.  Along  the  upper  surface  will  fre- 
quently be  found  saucer-shaped  structures  containing  small  buds 
which  are  capable  of  growing  into  new  plants;  a  non-sexual 
method  of  reproduction. 


THE  HEPATICiE  OR  LIVERWORTS 


167 


If  we  examine  a  cross-section  of  the  tliallus  under  a  com- 
pound microscope  we  will  find  the  epidermis  covering  a  large 
chamber  beneath  each  stomata.  Within  the  chamber  are  great 
numbers  of  delicate  chlorophyll  bearing  parenchyma  cells  while 
the  lower  cells  contain  little  or  no  chlorophyll. 

The  sexual  organs  are  borne  on  separate  plants.    The  female 


c" 

© 


c' 


©dl 


/ 


9' 


r 


FiQ.  108. — Diagrammatic  representation  of  the  life  cycle  of  Marchantia  polymorpha;  a', 
mature  male  plant;  a",  mature  female  plant;  b'  antheridium;  b"  archogonium;  c',  sperm; 
c",  ovum;  d,  oospore;  e,  young  sporoplyte;  f,  and  f",  spores;  g',  and  g",  young  plants. 

plants  (Fig.  107,  a)  bear  erect  stalks  supporting  radiating  struc- 
tures which  resemble  the  handle  and  ribs  of  an  umbrella  in  their 
arrangement.  On  the  under  surface  of  the  radiating  parts  will 
be  found  the  minute  flask-shaped  archegonia.  The  male  plants 
(Fig.  107,  h)  l>ear  erect  stalks  supporting  disk-shaped  Iwdies, 
on  the  upper  surface  of  which  will  be  found  minute  openings 
into  cavities  containing  the  antheridia.  The  fertilization  is 
the  same  as  in  the  ferns  and  mosses.     The  stalk  of  the  female 


168  BRYOPHYTES 

body  elongates  and  numerous  caj)SuJes  are  produced  on  the  under 
surface.  These  capsules  contain  numerous  spores  and  also  some 
spiral-shaped  bodies  known  as  elaters,  which  burst  the  capsules 
and  help  to  distribute  the  spores.  The  spores  grow  and  pro- 
duce new  plants.     (Fig.  108.) 

There  are  many  other  forms  of  liverworts,  some  of  which 
are  leafy  and  resemble  moss  plants,  and  are  frequently  mis- 
taken for  mosses. 

EXERCISES   WITH    imYOPTIYT'ES 

1.  Examine  a  moss  plant  and  note  the  cliaracter  of  its  stem  and 
leaves. 

2.  Examine  a  fruiting  moss  plant  and  note  the  setea,  capsule,  and 
calyptra.  Remove  the  calyptra  and  examine  with  a  hand  lens  for  the 
peristome. 

3.  Examine  a  non-fruiting  plant  of  the  Marchantia  poh/mnrpha 
and  note  shape,  surface  area,  stomata,  and  cupules  or  non-sexual  fruit inj; 
cups.  Scrape  some  of  the  rhizoids  from  the  under  surface  and  examine 
under  the  compound  microscope. 

4.  Cut  a  cross-section  and  examine  under  a  compound  microscope 
and  note  different  types  of  parenchyma  cells. 

5.  Examine  the  plants  which  are  carrying  the  fruiting  bodies. 

6.  Crush  a  capsule  and  examine  under  the  microscope;  note  spores 
and  elaters. 

QUESTIONS 

1.  To  what  great  group  do  the  mosses  and  liverworts  belong? 

2.  Describe  a  true  moss  plant. 

3.  Describe  the  thallus  of   the   liverworts. 

4.  How  and  where  are  the  sexual  organs  of  the  liverwort  borne? 
How  does  the  fertilization  take  place? 

,5.  What  are  the  most  striking  points  learned  in  your  study  of  Rry- 
ophytes? 


CHAPTER  XIX 
THALLOPHYTES 

We  have  now  come  to  the  lowest  great  division  of  the  plant 
kingdom,  the  Tliallophytes,  which  are  subdivided  into  three 
divisions,  the  Algce,  the  Fungi  and  the  Bacteria.  The  second 
and  third  of  these  groups  do  not  contain  chlorophyll  and  are 
therefore  quite  different  in  habit  from  all  other  groups  of  the 
plant  kingdom. 

The  algae  vary  greatly  in  both  size,  structure  and  color,  but 
all  of  them  contain  chlorophyll  and  are  able  to  do  the  work  of 
photosynthesis  or  starch-ni.aking.  The  range  from  the  small, 
one-celled  plant  which  cannot  be  seen  without  the  aid  of  the 
microscope,  through  delicate  thread-like  forms  up  to  the  enor- 
mous sea-weeds,  possessing  root-like,  stem-like  and  leaf-like 
organs.  They  are  widely  distributed  throughout  the  world  and 
are  of  much'  greater  importance  than  we  might  at  first  suppose. 
Minute  forms  are  found  in  great  numbers,  causing  the  green 
stain  on  the  bark  of  trees  and  stones  and  brick  walls,  in  the 
streams  and  pools,  and  in  the  seas,  gulfs  and  bays  and  even  the 
broad  ocean  itself. 

The  types  are  entirely  too  numerous  to  mention  in  a  work 
of  this  kind,  and  therefore,  we  must  content  ourselves  with  a 
study  of  two  or  three  of  the  most  common  forms.  Many  of  the 
unicellular  forms  found  in  moist  places  on  trees  and  walls  repro- 
duce by  simple  division,  each  division  resulting  in  the  forma- 
tion of  two  new  plants,  each  similar  to  the  parent.  Each  plant 
is  capable  of  performing  all  the  function  of  a  much  larger  and 
more  complex  plant ;  i.e.,  the  absorption  of  water  and  minerals 
in  solution  and  of  nitrogen,  tlie  taking  in  of  carbon  dioxide,  and 
photosynthesis  and  reproduction. 

169 


170 


THALLOPHYTES 


The  filamentous  forms  are  composed  of  single  rows  of  cells, 
each  cell  capable  of  sub-division,  and  if  separated  from  the 
others,  of  producing  a  new  plant.  The  very  common  Spirogyra 
(Fig.  109)  is  an  excellent  type  for  study.  The  cells  are  cylin- 
drical in  shape  and  attached  end-to-end.  Each  cell  contains  an 
imier  lining  of  protoplasm  and  numerous  cross  strands  of  the 
same  material ;  also  a  nucleus  which  may  be  located  in  any 
part  of  the  cell  but  usually  in  the  centre.  The  protoplasm  and 
nucleus  are  transparent  and  cannot  be  seen  readily  without  the 


Fio.  109. — Spriogyra: 
Fig.  110.— CEdogoniur 


single  cell   showing    chromatophore   and    nucleus;   b,  two    plante 

showing  sexual  reproduction, 
a,    plant   showing    non-sexual    cells;    b,  plant   showing  oogonium 
and  antheridium. 


use  of  an  artificial  stain.  The  spaces  between  the  strands  of 
protoplasm  are  known  as  vacuoles  and  are  filled  with  water. 
Embedded  in  this  protoplasm  will  be  readily  seen  the  spiral 
chrornatophores  or  chloroplasts  containing  the  chlorophyll.  Scat- 
tered along  this  chlorophyll  will  be  seen  the  round  shining 
pyrenoids  which  are  supposed  to  be  the  centres  for  food  forma- 
tion or  photosynthesis.  The  cell  of  the  spirogyra  may  be  looked 
upon  as  a  typical  plant  cell  in  which  all  the  functions  of  plant 
life  are  performed. 

Spirogyra. — Tf  we  examine  a  great  many  plants  of  spiro- 
gyra.  we  will  probably  find  some  specimens  which  are  attached 


OTHER  ALGM  171 

two-and-two  by  means  of  short  tubes,  the  one  plant  being  male 
and  the  other  female.  The  tubes  are  outgrowths  from  both 
plants  which  tend  to  unite ;  the  separating  walls  are  dissolved 
and  the  contents  of  the  male  cells  pass  into  and  unite  with  the 
contents  of  the  female  cells,  forming  what  is  known  as  zygo- 
spores, which  will  eventually  i)roduce  new  plants. 

Ulothrix  is  another  filamentous  form  which  produces  a 
large  number  of  ciliated  free-swimming  cells  known  as 
zoospores.  They  swim  for  a  time,  come  to  rest  and  each  grows 
into  a  new  plant.  In  some  cases  these  free-swimming  cells 
(gametes)  unite  in  pairs  and  form  zygospores. 

CEdogonium  (Fig.  110)  is  another  filamentous  form,  a  spe- 
cies which  presents  a  great  variation  in  sexual  character.  A 
cell  may  produce  a  single  large,  ciliated  cell  or  zoospore  which 
will  swim  for  a  time,  attach  itself  and  grow  into  a  new  plant. 
Or,  it  may  produce  a  large  female  cell  (gamete)  w^iicli  is 
retained  in  the  old  cell-wall  (oogonium)  and  fertilized  by  small 
free-swimming  zoospores  or  sperms  (gametes)  which  are  pro- 
duced by  another  cell  or  antheridium.  In  other  species  of 
G^dogonium  the  oogonia  are  produced  in  large  female  plants  and 
the  antheridia  in  the  small  male  plants. 

The  Vaucheria  are  filamentous  but  unicellular  and  multi- 
nuclear  forms.  The  non-sexual  reproduction  is  by  the  formation 
of  a  cross  wall  at  the  end  of  a  filament,  thus  forming  a  cell  from 
which  a  single  large  motile  or  non-motile  spore  is  produced.  The 
sexual  reprodiiction  is  by  the  formation  of  oval  oogonia,  each 
containing  a  single  large  ovum  or  egg  and  curved,  tubular  an- 
theridium containing  many  small  sperms.  The  sperm  escape 
and  at  last  one  reaches  the  ovum  which  is  fertilized  and  results 
in  an  oospore  or  resting  spore.  This  is  more  nearly  like  tlie 
liverworts,  mosses  and  ferns  than  most  of  the  alga?. 

Other  Algae. — Concerning  the  many  other  forms  of  algrp, 
wo  may  briefly  say  that  they  are  the  forests  and  the  i)astiires  of 


172  THALLOPHYTES 

the  waters  and  without  tlioiii  aiiiinal  life  in  the  water  would 
be  as  impossible  as  animal  life  on  the  land  without  land  plants. 
We  may  also  add  that  some  articles  of  conmierce,  such  as  iodine, 
are  obtained  from  the  algae,  and  the  time  may  not  be  far  distant 
when  the  enormous  beds  of  seaweeds  will  prove  a  valuable  source 
of  commercial  potash  for  fertilizers. 

The  fungi  are  surprisingly  like  the  algse,  but  differ  from 
them  in  the  fact  that  they  do  not  possess  chlorophyll.  There- 
fore, they  are  unable  to  do  the  work  of  photosynthesis  and  must 
depend  primarily  upon  organic  matter,  i.e.,  either  dead  or  living 
plants  or  animals,  for  their  food  supply.  Those  which  live  on 
dead  organic  material  are  saprophytes  and  tliose  which  live 
on  living  organisms  are  parasites.  We  wiU  give  brief  descrip- 
tions of  the  most  conmion  types. 

The  yeast  plants  {Saccliaromyces)  are  among, the  very  sim- 
plest in  structure.  They  are  very  minute,  spherical,  and  repro- 
duce by  budding.  They  are  found  abundantly  in  sugary  solu- 
tions and  are  extremely  important  in  alcoholic  fermentations. 
We  are  all  familiar  with  their  use  in  the  making  of  bread. 
Although  simple  in  structure  they  have  a  method  of  reproduc- 
tion which  takes  them  from  the  lowest  of  the  fungi. 

The  common  bread  mould  {Rliizopus  nigricans)  (Fig.  Ill) 
is  one  of  the  best  known  of  the  lower  fungi.  It  occurs  on  stale 
bread  kept  in  damp  places  and  appears  as  numerous  delicate, 
white  threads  containing  protoplasm,  both  in  the  bread  and  erect 
on  the  surface.  These  threads  are  called  myceliwn,  but  a  single 
one  is  often  called  the  hypha.  On  the  tips  of  the  hyphee  are 
numerous  spherical  sporangia  or  spore  cases  containing  spores. 
They  become  black  with  age,  burst  and  discharge  the  spores 
which  are  readily  carried  in  the  air. 

The  sexual  reproduction  is  by  the  formation  of  lateral 
branches  from  two  filaments.  These  branches  come  in  contact 
and  swell,  a  cell-w^all  is  formed  across  each  and  the  wall  at 


PARASITIC  FUNGI 


173 


the  point  of  union  is  dissolved,  permitting  the  union  of  the 
contents  of  the  two  cells.  This  results  in  the  formation  of  the 
zygospore  which  is  capable  of  giving  rise  to  a  new  plant.  The 
sexual  method  of  reproduction  rarely  occurs  in  nature. 

The  species  of  Saprolegnia    (Fig.  112)  are  parasitic  on  fish, 


sionally  on  decaying  food.  Thread-like  filaments  of  the  fungus 
grow  out  from  the  material  on  which  it  is  living.  Cross  walls 
or  septa  are  formed  in  these  filaments  and  great  numbers  of 


Fig.    111. — Ilhizopus   nigricans    or  bread    mould;    a,    entire   plant   showing   sporangia;    b, 
mature  zygospore. 

unicellular,  free-swimming  zoospores  will  be  produce<l  in  the 
apical  cell.  These  zoospores  escape,  swim  for  a  time,  become 
attached  to  suitable  food  material  and  produce  new  plants.  Cer- 
tain of  the  filaments  will  also  produce  antheridia  and  oogonia, 
giving  rise  to  oospores,  but  there  is  some  doubt  as  to  whether 
fertilization  really  occurs. 

Parasitic  Fungi. — The  downy  mildews,  powdery  mildews, 
and  many  other  fungi  are  parasitic  on  the  higher  plants  and  are 
causes  of  heavy  losses  to  our  agricultural  interests  every  year. 


174 


THALLOPHYTES 


^\juoiig'  the  most  iiitoresting  of  these  parasitic  fungi  are  the 
rusts  and  smuts,  some  of  which  are  very  destructive  to  our  grain 
crops.  Some  of  the  rusts  have  the  peculiar  habit  of  requiring 
two  distinct  host  phmts  in  order  to  complete  their  life  cycle. 
In  such  cases  they  have  two  or  more  stages,  one  occurring  on  one 
host  and  the  other  on  the  other  host;  the  spores  in  each  case 
will,  as  a  rule,  grow  only  on  tlio  o])posito  host  plant. 


Fig.  112. — Saprolegnia.    a,  infested  fly;    b,  immature  sporangium;    c,  mature  sporangium; 
d,  same  after  the  escape  of  the  spores;  e,  free  swimming  spores. 


The  fleshy  fungi  (Fig.  113),  many  of  which  are  spoken  of 
as  mushrooms,  and  toad-stools,  usually  grow  either  parasitically 
or  saprophytically  on  woody  plants.  Some  are  umbrella-shaped, 
while  others  are  shelving  in  character  and  still  others  are  the 
well-known  puff-balls. 

The  stipe  or  stem  of  the  mushroom  usually  rests  in  a  volva 
or  cup.  The  stipe  supports  tlie  pileus,  or  cap,  on  the  under  side 


OUR  GREATEST  INTEREST  IN  THE  FUNGI 


175 


of  which  we  find  the  gills  or  laniellic  on  the  snrface  of  which 
the  spores  are  borne.  We  freqiiently  speak  of  fnngi  as  growing 
very  rapidly  because  of  their  sudden  appearance  in  a  fully  de- 
veloped form.  However,  the  growth  is  not  nearly  so  rapid  as 
it  appears.  The  mycelium  may  grow  slowly  and  for  many 
months  in  the  tissues  of  the  host  plant,  which  it  is  slowly  eating 


Fig.  113. — Two  Bpecimens  of  mushrooms.     The  one  on  the  left  shou.s  the  annular  or  ring. 

away,  and  finally  come  to  the  surface  and  form  the  sporophores 
or  fruiting  bodies,  with  which  we  are  familiar,  in  a  very  few 
hours.  Some  few  fungi  are  used  for  food,  but  many  of  them 
are  deadly  poison  and  the  inexperienced  person  will  do  well  to 
refuse  all  forms  except  the  strictly  fresh  puff-balls. 

Our  greatest  interest  in  the  fungi  lies  in  the  fact  that  so 
many  of  them  are  parasitic  on  our  farm  crops  and  cause  the  loss 


176  THALLOPHYTES 

of  many  millions  of  dollars  every  year.  This  loss  is  so  enormous 
that  a  new  branch  of  botany,  known  as  plant  pathology,  has 
been  developed  for  the  study  of  plant  diseases  and  methods  for 
their  control. 

EXERCISES   WITH  THALLOPHYTES 

1.  Examine  algae,  as  many  as  circumstances  will  permit,  and  note  the 
points  referred  to  in  the  text.  The  algae  may  be  collected  from  small 
stream,9  and  kept  in  jars  and  dishes  on  tlie  laboratory  tables  for  many 
days  and  studied  with  the  aid  of  the  compound  microscope. 

2.  Collect  many  specimens  of  parasitic  fungi  found  on  leaves 
and  fruits  of  plants,  especially  on  cultivated  plants.  Study  them  in  their 
different  stages  of  reproduction. 

.3.  Develop  yeast  in  a  weak  solution  of  water  and  sugar  and  study 
specimens  under  the  microscope. 

4.  Keep  some  moistened  bread  in  a  warm  chamljer  (i.  r.,  under  an 
inverted  jar  or  in  a  closed  dish).  When  mould  has  developed  study  its 
different  stages. 

T).  Keep  some  dead  flies  in  an  open  bottle  of  water  and  watch  for 
the  development  of  Haprolegnia;  then  make  a  microscopic  study  of  it. 

QUESTIONS 

1.  What  three  groups  are  included  in  the  Thallophytes? 

2.  In  what  respect  do  all  the  algae  resemble  each  other? 

3.  Describe   reproduction    in   imicellular   algae. 

4.  Describe  reproduction   in  Spirogyra. 

5.  Describe    reproduction    in    Ulothrix. 

6.  Describe  the  forms  of  reproduction  in  Oedogonium. 

7.  How   is   reproduction    accomplished    in   Vaucheria? 

8.  Tell  of  the  economic  value  of  algae. 

9.  How  do  the  fungi  differ  from  alga-? 

10.  Describe  the  structure  of  yeast  plants. 

11.  W'hat  is  the  structure  of  bread  mould?     Tell  of  its  reproduction. 

12.  Give  examples  of  parasitic  fungi.     Of  what  importance  are   they? 

13.  Tell  what  you  can  of  the  fleshy  fungi. 

Reference. — Read  accounts  of  algae  and  of  fungi,  found  in  an  encyclo- 
pedia and  special  books  on  these  subjects. 


CHAPTER  XX 
BACTERIA 

Bacteria  are  the  smallest  of  all  plants  and  in  fact  some  of 
tlieni  are  the  smallest  known  organisms.  It  would  require 
125,000  of  the  smaller  ones,  placed  side  by  side,  to  make  a  line 
one  inch  long.  They  are  like  the  fungi  in  that  they  do  not  con- 
tain chlorophvll  and  cannot  perform  the  work  of  photosynthesis. 
Therefore,  they  are  either  saprophytic  or  parasitic.  Some  are 
motile  and  others  non-motile.  They  multiply  by  simple  cell 
division  and  many  species  form  resting  spores  which  enable  them 
to  resist  extremes  of  temperature  and  humidity. 

Abundance. — Bacteria  are  more  abundant  than  other  forms 
of  life.  They  float  in  the  air  that  we  breathe,  are  in  the  water 
that  WQ  drink  and  the  food  that  we  eat.  They  are  to  be  found 
in  our  mouths,  lungs,  stomach,  and  intestines.  They  cause  the 
souring  of  milk,  the  fermentation  of  various  liquids,  the  decay 
of  fruits,  vegetables  and  meats.  Fortunately  the  great  major- 
ity are  harmless  and  many  are  beneficial.  Among  the  most 
interesting  of  the  beneficial  species  are  those  which  are  involved 
in  the  fixation  of  nitrogen.     (Page  117.) 

Causes  of  Disease. — However,  many  bacteria  are  the  causes 
of  diseases  of  both  plants  and  animals.  Among  the  most  serious 
of  plant  diseases  caused  by  bacteria  are  the  fire  blight  of  the 
pear  and  apple,  the  black  rot  of  cabbage  and  related  plants  and 
the  root  or  crown  gall  of  our  fruit  trees  and  many  other  plants. 
]\rany  serious  animal  diseases  are  caused  by  bacteria  such  as 
tuberculosis  or  consumption,  diphtheria,  tetanus  or  lockjaw, 
grippe,  anthrax,  cholera  and  many  others  which  attack  man 
and  the  lower  animals. 

12  177 


178  BACTERIA 

With  our  increasing  knowledge  of  these  diseases  we  are 
learning  to  combat  them.  We  are  learning  how  to  cure  patients 
suffering  from  them  and  also  how  to  prevent  them.  It  is  an 
old  saying  that  "  an  ounce  of  prevention  is  worth  a  pound  of 
cure,"  and  we  are  learning  that  proper  sanitation,  the  removal 
of  filth  in  which  the  bacteria  breed,  the  protection  of  drink- 
ing water,  the  destruction  of  flie--,  mosquitoes  and  other  insects 
that  carry  bacteria,  and  personal  cleanliness  are  great  helps  in 
the  prevention  of  bacterial  diseases. 

The  study  of  bacteria  has  resulted  in  the  development  of 
a  branch  of  applied  botany  known  as  hacteriology  which  is  re- 
ceiving a  great  deal  of  attention,  especially  in  our  Universities 
and  Medical  Colleges. 

The  Myxomycetes  (Mycetozoa)  or  Slime  Mounds. — These 
are  forms  of  life  which  possess  both  plant  and  animal  charac- 
teristics. They  are  truly  on  the  border  between  the  plant  and 
animal  kingdoms.  They  are  found  in  the  water  or  on  wet  soil 
or  decaying  vegetables  as  naked  slimy  masses  of  protoplasm, 
called  Plasmodia.  They  move  very  slowly  by  a  peculiar  creep- 
ing movement  similar^  to  that  of  the  amceha,  which  is  one  of  the 
lowest  forms  of  animal  life.  This  plasmodium  has  the  char- 
acteristics of  the  species  to  which  it  belongs  and  finally  produces 
great  numbers  of  spores,  similar  to  those  of  some  of  the  fungi. 
These  spores  eventually  give  rise  to  minute  one-celled  amoeboid 
individuals  which  unite  to  form  a  new  and  growing  plasmodium. 
One  species  of  this  group  (Plasmodiophora  hrassicce)  is  the 
cause  of  the  very  common  and  serious  club  root  disease  of 
cabbage. 

EXERCISES   WITH  BACTERIA. 

1.  Put  a  few  small  shreds  of  meat  into  two  flasks  of  water.  Boil  both 
for  thirty  minutes  or  more;  plug  one  with  cotton  immediately;  leave  the 
other  open  and  set  both  away  for  a  few  days.  Examine  them  from  time 
to  time  and   note  diflcrences   in  their  appearance.     When   they  show  very 


QUESTIONS  179 

noticeable  differences  examine  a  drop  of  each  under  the  compound  micros- 
cope.    What  do  you  see?     What  has  caused  the  difference? 

QUESTIONS 

1.  What  can  you  say  of  tlie  importance  and  abundance  of  bacteria? 

2.  What  plant  diseases  are  caused  by   bacteria? 

3.  Tell  of  the  character  and  occurrence  of  the  slime  moulds. 

4.  Why   do  canned   fruits   and  vegetables  keep?     Why   do  they  occa- 
sionally spoil? 


PART  II 

MOST  IMPORTANT  FAMILIES  OF  ECONOMIC 
PLANTS,  WITH  SPECIAL  EXERCISES 


CHAPTER  XXI 

IMPORTANT  FAMILIES  OF  PLANTS 

First  Uses  of  Plants  by  Man. — The  origin  and  development 
of  agricultnre  are  veiled  in  the  mystery  and  tradition  of  the 
early  civilization  of  the  human  race.  The  early  historical  records 
are  incomplete  and  no  one  knows  just  when  the  different  races 
began  the  practice  of  agricultnral  methods.  Traditions  con- 
nected with  some  plants  tell  us  that  they  were  introduced  by 
gods  or  by  kings.  It  may  be  that  the  introduction  of  some  plants 
date  from  the  reign  of  certain  great  monarchs,  but  in  most  cases 
these  traditions  are  of  doubtful  value. 

It  is  very  probable  that  most,  if  not  all,  races  of  people  were 
more  interested  in  war,  hunting  and  fishing  than  in  agriculture, 
and  that  under  these  circumstances  the  beginnings  of  agriculture 
must  have  been  feeble,  interrupted  and  obscure.  The  destruc- 
tion and  abandonment  of  growing  crops  by  war  or  in  the  search 
of  better  hunting  grounds  was  not  conducive  to  the  advance- 
ment of  agriculture. 

Early  agriculture  must  have  developed  very  slowly,  and  as 
a  result  of  necessity,  or  because  it  made  life  easier  for  the 
individual  and  the  tribe.  These  early  beginnings  probably 
originated  in  the  gathering  and  storing  of  wild  crops,  followed 
first  by  a  protecting  of  these  wild  crops  from  the  ravages  of 
wild  animals  and  other  tribes,  then  by  the  increasing  of  their 
range  by  scattering  seeds,  and  finally  by  cultivation.  This  last 
step  very  naturally  led  to  improvements  in  methods  and  the 
selection  of  the  most  valuable  plants. 

Our  earliest  records  of  agriculture  concern  Egypt  and 
China,  but  it  is  very  likely  that  agriculture  was  practiced  in 
India  and  other  parts  of  Asia  as  early  as  in  China.     There  was 

183 


184  IMPORTANT  FAMILIES  OF  PLANTS 

aiso  a  very  ancieut  agriculture  iu  parts  of  America,  but  it  is 
very  doubtful  if  it  is  as  old  as  the  eastern  agriculture. 

Maukind  very  naturally  began  to  cultivate  those  plants  which 
they  had  previously  used  from  the  wild  and  the  practice  very 
naturally  tended  to  discourage  their  nomadic  habits.  Increas- 
ing population  very  naturally  made  greater  and  greater  demands 
on  agriculture  and  resulted  in  improved  methods,  the  selec- 
tion of  the  best  plants  and  the  introduction  of  new  plants. 

Westward  Movements. — But  man  could  not  give  up  his 
old  nomadic  habits  quickly.  His  love  for  the  chase,  for  travel 
and  exploration,  for  war  and  conquest  were  strong  and  must  bo 
satisfied  by  actual  experiences.  Therefore,  we  see  certain 
great  movements  of  the  human  race,  such  as  the  migrations  of  the 
early  Christians  from  Judea  westward,  the  Crusaders  from 
Europe  back  to  the  Holy  Land  and  their  return  to  Europe,  the 
discovery,  conquest  and  settlement  of  America.  These  and  many 
other  similar  movements  of  greater  or  less  proportions  very 
naturally  resulted  in  the  introduction  of  many  new  and  vahiable 
plants  into  countries  in  which  they  were  previously  unknown. 

The  history  and  origin  of  our  agricultural  plants  is  obscure 
and  in  some  cases  the  confusion  is  increased  by  the  names  which 
many  of  the  plants  bear.  The  English  walnut  is  from  Persia 
and  not  England,  the  Irish  potato  is  from  Peru  and  Equador 
and  not  Ireland,  the  peach  (Prunus  persica)  is  from  China,  but 
went  into  Europe  by  way  of  Persia. 

A  knowledge  of  our  most  important  cultivated  plants  would 
be  well  worth  while  and  very  interesting.  It  is  of  much  greater 
importance  than  a  knowledge  of  wild  flowers,  although  this  line 
of  work  should  not  be  neglected.  All  of  our  cultivated  plants 
were  originally  wild  plants,  and  in  recent  years  many  of  these 
so-called  "  wild  plants,"  such  as  alfalfa  and  sweet  clover,  have 
been  brought  under  cultivation.  Useful  plants  of  our  own  part 
of  the  world  may  be  of  very  little  value  in  other  parts. 


CABBAGE  185 

IMPORTANT  ECONOMIC  FAMILIES  OF  PLANTS 

Students  should  familiarize  tliemselves,  in  so  far  as  pos- 
sible, with  representative  plants  in  the  following  families,  by 
studying  the  living  plants  where  possible,  and  by  giving 
special  attention  to  their  commercial  importance.  Most  of  these 
families  are  represented  by  plants  which  are  common  to  our 
farms ;  the  fruits  of  others  can  be  secured  on  the  local  markets ; 
and  the  historical  accounts  and  commercial  uses  will  furnish 
important  lines  of  study.  The  studies  of  these  families  may  be 
supplemented  by  others  that  are  convenient  or  of  local 
importance. 

MUSTAED   FAMILY    (cKUCIFER.e) 

The  flowers  of  this  family  are  usually  borne  in  terminal 
racemes;  usually  white  or  yellow;  four  petals;  four  sepals  ar- 
ranged in  form  of  a  cross ;  four  long  and  two  short  stamens  and 
two  stigmas  on  a  single,  two-chambered,  many-seeded  ovary. 
The  plants  are  mostly  herbaceous,  sometimes  woody,  with  cylin- 
drical or  angular  stemsi  and  with  a  pungent,  watery  juice.  The 
leaves  are  simple,  usually  alternate,  entire,  lobed  or  bisected 
and  without  stipules.  The  fruit  is  long,  slender  and  pod-like. 
None  of  these  plants  are  poisonous.  Many  members  of  this 
family  of  plants  are  very  useful  as  vegetables,  forage  crops 
and  in  medicines.  Let  us  consider  a  few  of  the  most  common 
and  important. 

Cabbage  (Brassica  ohracece  L.)  (Fig.  114). — This  well- 
known  plant  is  derived  from  a  wild  plant  in  the  south  of  Eng- 
land and  other  parts  of  western  Europe.  It  is  perennial,  pro- 
ducing yellow  flowers  and  abundant  seeds  the  second  year. 
Plants  selected  for  seed  are  put  in  trenches  and  covered  with 
soil  for  the  winter.  They  are  reset  the  following  spring,  bloom 
and  produce  seed  abundantly.     Cabbage  seed  growing  is  a  well- 


186 


IMPORTANT  FAMILIES  OF  PLANTS 


developed  industry  in  some  parts  of  the  country.  It  is  not  known 
when  the  cabbage  was  first  used  as  food.  It  is  referred  to  in 
literature  antedating  the  Christian  Era  by  about  three  hundred 
years,  and  it  is  now  very  generally  used  throughout  the  world. 
There  are  many  important  commercial  varieties.  These  may 
be  classified  into    (a)    the  early  or   short-season  group,  with 


Fio.  114. — The  spherical  form  of  cabbage. 

small  round  or  pointed  heads,  as  Jersey  Wakefield;  (b)  the  late 
or  long-season  group,  with  large  round  or  flat  heads,  as  Drum- 
head and  Flat  Dutch.     All  endure  spring  and  fall  frosts. 

Cauliflower  (Fig.  11 5), Brussels  sprouts.  Kale  and  Kohl-rabi 
(Fig.  IIG)  are  derived  from  the  same  wild  plant. 

Mustards  (B.  alba  Gray  and  B.  nigrw  Koch). — These  well- 
known  ]ilants  are  annuals  and  produce  seeds  of  considerable  com- 


CABBAGE 


187 


Fig.  115. — Cauliflower,  with  outer  leaves  trimmed. 


lie.  no.-  Kuhl  labi  uf  edible  .-iizc. 


\ 


188 


IMPORTANT  FAMILIES  OF  PLANTS 


mcrcial  importance.     Tliey  are  used  in  the  preparation  of  foods 
and  also  as  medicines.     Their  nso  antedates  the  Christian  Era. 


Fig.  117. — The  flat  form  of  true  turnip  with  white  fie.sh. 

Field  Turnips  {B.  campedris)  and  tiiie  turnips  {B.  rapa) 
(Fig.  117)  are  well  known  plants  used  for  food  for  both  man 
and  beast.     They  originated  in  northern  Europe  and  Asia  and 


VIOLET  FAMILY  189 

their  use  also  antedates  tlie  Cliristiau  Era,  but  they  were  not 
grown  extensively  until  early  in  the  seventeenth  century.  Seed 
turnips  are  also  kept  and  grown  the  second  season  in  the  same 
manner  as  the  cabbage. 

There  are  several  types  and  varieties  of  the  true  or  flat 
turnips.  Those  with  white  flesh  are  most  popular,  but  the 
yellow-fleshed  sorts  are  also  g•ro^vn.  The  field  turnip,  or  ruta- 
baga, has  yellowish  flesh  and  is  rich  in  flavor.  They  produce 
heavier  yields  than  other  turnips. 

The  radish  (Raphanus  sativus),  the  horseradish  {Coch- 
learia  armoracia),  the  rape  {Brassica  7iapa),  and  the  water 
cress  {Nasturtium  officinale)  and  many  other  valuable  plants 
belong  to  this  family.  Most  of  them  originated  in  the  tem- 
perate regions  of  Europe  and  Asia,  and  their  use  and  cultivation 
dates  back  to  a  very  early  period  in  history. 

All  of  these  plants  are  grown  from  the  seeds  which  are 
usually  sown  direct  in  the  soil  in  which  they  are  to  be  grown. 
The  water  cress  is  usually  started  by  transplanting  from  one 
locality  to  another.  The  mustards  frequently  escape  cultiva- 
tion and  become  troublesome  weeds.  This  family  also  includes 
wild  radish,  field  cress  and  many  other  weeds  M'hich  are  more 
or  less  troublesome.  However,  most  of  them  are  annuals  or 
biennials  and  can  be  controlled  by  using  a  crop  requiring  fre- 
quent cultivation  or  if  growing  in  wheat  or  oats  by  spraying 
with  sulphate  of  iron. 

VIOLET   FAMILY    (vIOLACE.e) 

Flowers  perfect,  irregular,  axillary,  usually  solitary,  two 
bracts  at  base  or  near  the  middle  of  each  pedicel.  Five  sepals 
which  are  usually  free  and  persistent ;  five  petals  which  are 
hypogynous  and  alternate  with  the  sepals,  unequal  in  size,  the 
lower  one  forming  a  hollow  spur;  five  stamens  inserted  on  lower 


190 


IMPORTANT   FAMILIES  OF  PLANTS 


part  of  calyx;  fruit  a  three-parted  pod  with  parietal  placenta 
leaves  alternate  and  stipulate. 

This  family  includes  the  many  species  and  varieties  of 
violets.  These  flowers  were  known  through  practically  all  his- 
torical time  and  are  now  grown  very  extensively  to  supply  the 
flower  markets  of  our  cities.  The  cultivated  pansy  is  a  species 
of  violet  {V.  tricolor)  (Fig.  118). 


n 


,§ 


0^, 


./^#.^ 


Fig.  118. — Pansies  are  so  hardy  as  to  stand  much  frost. 

Commercial  violets  are  grown  from  cuttings  which  are 
started  in  cool  greenhouses.  Common  varieties  of  pansies  are 
grown  from  seeds,  but  some  of  the  more  important  com- 
mercial varieties  are  grown  from  layers  or  from  cuttings  made 
late  in  the  season.  If  pansy  beds  are  covered  in  the  fall  with 
a  loose  layer  of  grass  or  leaves,  they  will  usually  survive  the 
winter  and  be  more  vigorous  the  second  than  the  first  vear. 


COTTON  191 

MALLOW  FAMILY   (  MALVACEAE  ) 

The  plants  of  this  family  are  either  herbs  or  shrubs.  The 
flowers  have  five  sepals  united  at  the  base,  five  petals,  many 
stamens  and  a  single-  one-chambered  ovary  with  many  pistils. 
The  mature  fruit  is  a  capsule. 

Cotton. — In  this  family  we  find  the  cotton  plants  (Gos- 
sypium  herhaceum  L.,  G.  barhadense  L.,  G.  arboreum  L. )  which 
are  among  the  most  valuable  of  the  fibre  or  lint  plants.  The 
fibre  is  produced  on  the  seeds  within  the  capsule.  The  cotton 
plant  was  used  long  before  Christ.  It  probably  originated  in 
India  and  spread  throughout  the  tropical  and  subtropical  parts 
of  the  world,  although  the  early  Spanish  explorers  claim  to  have 
found  it  growing  in  Mexico  and  Central  America  and  that  the 
natives  were  using  it  for  making  clothing.  It  is  one  of  the  most 
important  cro])s  of  the  southern  states  and  is  used  for  many 
purposes  other  than  that  of  making  clothing,  such  as  gun-cotton 
and  collodion.  The  oil  is  extracted  from  the  seeds  and  used  for 
culinary  purposes  and  as  a  substitute  for  olive  oil  and  the  re- 
maining solid  part  of  the  seed  is  used  for  stock  feed.  Cotton- 
seed meal  is  also  used  extensively  as  a  fertilizer  for  the  soil. 

Accepting  the  idea  that  cotton  is  a  native  of  both  the  old 
and  the  new  world,  it  is  evident  that  G.  herbaceum  is  the  old 
world  form,  G.  arboreum  (tree  cotton)  the  African  form  and 
G.  barbadense  the  American  type.  Many  varieties  of  types  are 
now  recognized;  one  of  the  most  popular  of  our  American  types 
is'  the  "  sea  island  "  or  "  long  staple  cotton  "  which  is  a  variety 
of  G.  barbadense. 

The  fruit  of  the  okra  or  gumbo  (Hibiscus  esculent  us  L.) 
(Fig.  110)  is  extensively  used  in  soups,  stews  and  catsups,  espe- 
cially in  the  southern  part  of  the  United.  States.  Its  origin  is 
unknown,  but  it  probably  originated  in  Africa  or  the  American 
tropics. 


192 


IMPORTANT  FAMILIES  OF  PLANTS 


Fig.  119. — Pods  of  okra  or  gumbo  in  green  and  ripe  stages. 


FLAX  FAMILY  193 

The  Hollyhocks  {Althwa  rosea)  (Fig.  120),  mallows  and 
some  other  interesting  ornamental  plants  belong  to  this  family. 
Most  of  the  members  of  this  family  are  grown  from  seeds, 
but  the  hollyhocks  and  related  forms  persist  from  year  to  year. 
The  cheese  (MaJva  rotundifolia)  and  the  Indian  mallow  or  vel- 
vet weed  {Ahidilon  abutilon)  are  common  weeds. 

STEECULIA  FAMILY    (STEKCULIACE^) 

The  members  of  this  family  are  trees  or  shrubs  somewhat 
similar  to  the  Malvaceae,  but  the  capsules  are  much  larger  and 
are  fleshy.  Here  we  find  one  of  the  very  important  plants  which 
America  gave  to  the  world,  the  cocoa  or  chocolate  plants — 
{Theohroma  cocoa).  It  is  tropical  and  was  taken  to  Europe  by 
the  Spaniards  about  1520,  but  it  was  more  than  a  hundred  years 
before  its  spread  to  England.  It  is  now  cultivated  in  other  parts 
of  the  world,  but  the  greater  part  of  the  supply  comes  from  trop- 
ical America. 

FLAX  FAMILY    (lUSTACE.e) 

Herbaceous,  slightly  woody  plants  with  perfect,  regular 
flowers,  borne  in  terminal  racemes  or  corymbs.  Five  sepals,  oc- 
casionally four,  hypogynous;  stamens,  same  number  as  petals 
and  alternate  with  them ;  style  three  to  five ;  ovary  five  to  four 
chambers  with  two  ovules  in  each  chamber ;  fruit  capsular. 

Flax  (Linum,  usitatissimuni  and  L.  angustifolium)  is 
one  of  the  most  important  fibre  plants.  It  is  supposed  to  have 
originated  in  some  of  the  Mediterranean  or  Far  East  countries, 
but  its  use  as  a  fibre  plant  began,  long  before  the  Christian  Era. 
This  is  a  very  important  crop  in  some  parts  of  the  United  States, 
especially  in  Minnesota  and  the  Dakotas.  It  is  grown  pri- 
marily for  the  fibre  which  is  used  in  the  manufacture  of  linen 
and  for  the  seed  from  which  the  linseed  oil  of  commerce  is 
extracted. 
13 


194 


IMPORTANT  FAMILIES  OF  PLANTS 


Fig.  120. — Hollyhock,  representing  the  flower  type  of  the  mallow  family. 


RUE  FAMILY 


195 


The  oil  is  used  in  the  manufacture  of  paints,  varnishes, 
patent  leather,  linoleum  and  other  products.  The  cake  and  meal 
left  after  extracting  the  oil  is  used  extensively  for  stock  feed. 


Fig.  121. — The  sweet  orange,   often  nearly  seedless. 
EUE  FAMILY    (rUTACEJe) 

Shrubs  and  small  trees  with  perfect  flowers.  Five  sepals ; 
five  to  ten  petals;  many  stamens;  style  one,  ovary  ripening  into 
a  many-chambered  berry,  capsule  or  samara. 


196 


IMPORTANT  FAMILIES  OF  PLANTS 


The  sweet  orange  (Citrus  aurantium)  (Fig.  121)  is  the 
best-known  and  most  important  fruit  of  this  family.  No  one 
knows  just  where  the  orange  came  from  or  where  it  was  first 
used  by  man,  but  it  probably  came  from  South  China  or  India 
and  was  brought  into  Europe  by  the  returning  Crusaders  or  the 
Moorish  invasion  of  Spain  or  possibly  both.  It  was  introduced 
into  America  by  the  early  Spanish  explorers. 

The  grapefruit  (C.  decumana),  the  lemon  (C.  limonum). 


Fig.  122. — Modern  improved  grape. 

the  lime  (C.  limeita)  and  the  citron (C.  medica)  are  important 
members  of  this  genus. 

VINE  FAMILY   (viTACEiE) 

This  family  is  made  up  of  shrubs,  usually  climbing  by  means 
of  tendrils ;  alternate,  simple  or  compound  leaves ;  flowers  min- 
ute, greenish,  perfect  or  imperfect;  calyx  entire  or  four  to  five 
toothed ;  petals  four  or  five,  separate  or  united  and  disappearing 
very  soon  after  development ;  stamens  four  or  five  and  opposite 
the  petals ;  pistil  one,  consisting  of  two  to  six  chambers ;  fruit 
usually  a  two-celled  berry. 


PROPAGATION 


197 


In  this  family  we  find  the  grape  (Fig.  122),  which  is  thought 
to  be  the  oldest  of  the  cultivated  fruits.  The  very,  very  early 
historical  records  refer  to  grape-growing  and  wine.  The  most 
important  grape  of  the  old  world  is  the  Yitis  vinifera,  which  is 
probably  of  Asiatic  origin.  In  Europe,  the  grape  is  grown 
largely  for  wine,  but  it  is  also  grown  for  raisins  and  other 
purposes.  The  effort  to  introduce  the  European  grapes  into  the 
American  colonies  was  a  failure,  owing  to  the  fungous  diseases 
and  insects  which  destroyed  them.     But  in  time  a  number  of 


Fig.  123. — Grape-vine  cuttings  of  four  forms.  A,  one  bud  or  single  eye;  B,  simple 
cutting  showing  two  buds;  C,  heel  cutting  with  some  of  the  wood  of  the  larger  stem; 
D,  mallet  cutting,  with  a  piece  cut  out  of  the  larger  stem.     (.Productive  Farming.) 

good  varieties  were  developed  from  the  native  American  grapes. 
Among  the  most  important  are  the  Concord  and  Catawba  types 
from  V.  lahrusca  and  the  Scuppernong  from  the  V.  rotundi- 
folia.  With  the  spread  of  civilization  westward,  the  European 
grape  has  been  introduced  into  southern  California.  In  America 
the  grapes  are  grown  primarily  for  food  instead  of  for  the  pro- 
duction of  wine. 

Propagation. — Grapes  are  usually  propagated  by  means  of 
cuttings,  but  can  be  grafted  without  great  difficulty.  Four  com- 
mon forms  of  grape  cuttings  are  shown  in  Fig.  12.3.  It  is 
usual  with  our  varieties  east  of  the  Mississippi  to  use  simple 
cuttings  with  two  or  three  buds,  shown  at  b  in  the)  figure.     Cut- 


198  IMPORTANT  FAMILIES  OF   PLANTS 

tings  are  made  in  early  winter  and  stored  in  wet  sawdust  in  a 
cool  cellar.  Here  they  fonn  calluses  over  the  wounds  and  elab- 
orate the  food  stored  in  the  tissues,  aud  are  ready  to  grow  when 
set  in  the  soil  in  the  spring. 

Some  varieties  are  rooted  in  sharp  sand  under  glass.  Others 
are  commonly  planted  in  garden  soils  deep  enough  to  allow  only 
one  bud  to  show.  The  soil  should  be  tramped  firmly.  The 
planting  is  done  after  all  danger  of  frost  is  over.  They  are  set 
a  few  inches  to  one  foot  apart  in  rows,  and  the  rows  far  enough 
apart  to  allow  of  clean  cultivation.  They  should  become  well 
rooted  and  make  some  growth  the  first  year  in  the  garden  or 
nursery.  They  may  be  then  transplanted  to  the  permanent  vine- 
yard. The  distances  apart  in  vineyards  yarj  from  six  to  twelve 
feet,  depending  upon  varieties,  method  of  trellising,  and  style 
of  pruning  to  be  used.  The  history  of  grape  growing  in  America 
is  extremely  interesting  and  well  worth  reading.  An  excellent 
account  is  given  in  Bailey's  "  Evolution  of  Our  iSTative  Fruits." 

This  family  also  includes  the  Virginia  creeper,  Boston  ivy, 
and  some  other  ornamental  vines. 

SOAP  BERRY  OR   MAPLE  FAMILY    (aCERACE.e) 

This  family  includes  many  shrubs  and  trees,  with  saccharine 
sap ;  leaves  opposite,  simple  or  palmately  lobed,  occasionally 
palmately  or  pinnately  divided ;  flowers  small,  regular,  usually 
polygamous  or  dioecious,  occasionally  apetalous ;  pistil  one, 
two-chambered. 

Maples. — This  family  contains  the  maples  (Fig.  124)  of  the 
genus  Acer  which  are  very  important  as  shade  and  ornamental 
trees.  Among  the  most  important  of  our  native  species  are  the 
silver  maples  (A.  saccharinum.) ,  the  red  or  scarlet  maples  {A. 
ruhrum).,  the  sugar  or  rock  maples  (A.  saccharinum),  the  box 
elder  (A.  ner/imdo)  and  others.    The  T^orway  maple  (.1.  platan- 


PEA  FAMILY 


199 


oides)  is  used  extensively  for  shade  and  the  Japanese  species 
are  used  extensively  for  ornamental  purposes. 

A  very  excellent  grade  of  sugar  is  made  from  the  sap  of 
the  sugar  maple  and  its  manufacture  forms  a  very  important 
industry  in  some  parts  of  the  country,  especially  in  the  Nevr 
England  States  and  the  northern  states  farther  west.  In  the 
early  history  of  the  country,  this  was  the  most  important  and 
in  many  cases  the  only  source  of  sugar  for  the  early  settlers. 


\^   V^"*^- 


,-J'^^-4%^^» 


m 


Fig.  124. — Maple. 


Most  species  are  grown  from  seeds  sown  one  or  two  inches 
deep.  The  seeds  of  the  early  ripening  species  will  not  retain 
their  vitality  until  the  following  spring  and,  therefore,  should 
be  sown  as  soon  as  possible  after  they  fall  from  the  tree.  They 
can  also  be  grown  from  layers  and  by  gi*afting.  Some  fancy 
species  and  varieties  are  always  propagated  in  this  manner. 

PEA  FAMILY   (lEGUMINOSE^) 

This  family  includes  herbs,  shrubs,  trees  and  vines ;  leaves 
alternate  and  usually  odd-pinnately  compound,  with  stipules; 


200 


IMPORTANT  FAMILIES  OF  PLANTS 


flowers  mostly  irregular  and  often  showy  and  papilionaceons 
{i.e.,  biitterfly-like )  ;  calyx  four  to  five  cleft;  corolla  usually  of 
tivo  ])«'t;ils  which  may  be  united  (as  in  the  case  of  the  clover) 

or  only  partly  united  (as  in 
the  pea)  ;  stamens  unusu- 
ally 10  with  all  the  stamens 
united  {monadelphous)  or 
nine  united,  and  one  free, 
but  forming-  a  tube,  enclos- 
ing the  pistil ;  pistil  one, 
with  one  chamber  fruit  usu- 
ally a  legume  or  pod. 

This  is  one  of  the  most 
important  families,  econom- 
ically, to  be  found  in  the 
plant  kingdom.  It  contains 
nearly  four  hundred  and 
fifty  genera  and  more  than 
seven  thousand  species, 
many  of  which  are  impor- 
tant agricultural  crops. 
They  include  cultivated 
crops  used  as  food  for  man 
and  beast;  forest  trees  and 
ornamentals.  The  growing 
of  leguminous  crops  is  also 
recognized  as  one  of  the  best 
methods  of  improving  the 
soil. 

Legumes  Gather  Nitrogen.— The  use  of  legumes  in  the 
improvement  of  soils  depends  upon  the  partnership  (or  symbi- 
osis) existing  between  these  plants  and  certain  nitrogen- 
gathering  bacteria  which  make  their  homes  on  the  roots  (Fig. 


plant 


th   nocluk 


Fig.  12"). — Red  clover 
on  the  roots,  containing  bacteria  which  enable 
the  plant  to  gather  nitrogen  from  soil  air.  (Fight 
of  the  Farmer.) 


LEGUMES 


201 


125).  The  nodules  seen  on  the  roots  are  the  homes  of  the  bac- 
teria. When  the  bacteria  are  present  on  the  roots  the  phints 
are  enabled  to  gather  nitrogen  from  the  air.  This  power  is 
not  found  in  other  families  of  plants. 

The  relationship  existing  between  the  plants  of  the  legume 
family  and  the  bacteria  on  the  roots  is  a  kind  of  partnership 
(or  symbiosis).  The  clover  plant,  for  example,  furnishes 
homes  for  the  bacteria  and  supplies  tliem  with  nourishment. 


Fio.  12tt. — Pod  and  seeds  of  lima  bean. 

In  return  for  these  benefits,  the  bacteria  enable  the  clover  plant 
to  gather  nitrogen  from  the  air  and  use  it  in  its  own  growth. 

Different  kinds  of  bacteria  are  found  to  suit  the  different 
legumes.  The  red  clover  bacteria  do  not  tlirive  on  alfalfa  or 
on  beans.  There  are  some  forms  of  bacteria  that  are  adapted 
to  several  legumes.  For  example,  those  on  alfalfa  are  also 
found  on  sweet  clover  and  on  bur  clover. 

Legumes  aid  other  crops   grown   in   the  same  soil   after 
them.     Tf  clover  or  cowpeas,  for  example,  are  plowed  under, 


202 


IMPORTANT  FAMILIES  OF  PLANTS 


tlio  nitrogen  which  thev  have  gathered  and  stored  in  their 
leaves,  stems  and  roots  is  added  to  the  soil  This  may  soon  be 
changed  to  forms  which  corn,  potatoes,  or  other  crops  may  nse 
while  growing  in  that  soil. 

Beans. — The  term  "  bean  "   is  applied  to  many  plants  of 
this  family;  the  broad  bean   (Vicia  faba)   is  of  Asiatic  origin 


I 


Fig.  127. — Alfalfa  and  clover. 


and  is  extensively  grown  in  Europe  for  the  feeding  of  live  stock ; 
the  kidney  bean  (Phaseolus  vulgaris)  probably  originated  in 
tropical  America  and  is  represenjted  by  many  species  and 
varieties  of  garden  and  field  beans  which  are  so  extensively 
grown  throughout  the  world;  the  Lima  bean  (P.  lunatus)  (Fig. 
126)  is  a  native  of  South  America,  the  soy  or  soja  bean 
{Glycine  hispida)  is  of  Asiatic  origin  and  is  gro^vm  extensively 
for  stock  feed ;  the  so-called  cowpea  or  bean  (  Vigna  simensis)  is 


PEANUT  203 

silso  grown  extensively  for  the  same  purpose ;  the  scarlet  runner 
(P.  muUiflorus)  is  an  interesting  ornamental. 

Peas. — The  common  garden  pea  {Pisum  sativum)  is  well 
known  as  one  of  our  most  valuable  garden  crops  and  is  fre- 
(juently  grown  very  extensively  for  canning. 

Clovers. — The  genus  TrifoUum  includes  about  three  hun- 
dred species  of  clovers  (Fig.  127),  many  of  which  are  num- 
bered among  our  most  important  agricultural  crops. 

The  most  important  clovers  are  the  red  clover  (TrifoUum 
pratense  L.)  the  mammoth  clover  {T.  medium),  the  white 
clover  {T.  repens),  the  alsike  or  Swetlish  clover  (T.  hy- 
hridum)   and  the  crimson  or  scarlet  clover   {T.  incarnatum). 

The  term  clover  is  also  often  applied  to  other  genera,  such 
as  the  alfalfa  (Medicago  sativa)  (Fig.  127),  the  commou  yellow 
clover  or  trefoil  (M.  lupulina),  the  bur  clover  (M.  denticulcUa), 
the  sweet  clovers  (Meiilotus  alba,  M.  officinalis),  the  bush  or 
Japan  clover  (Lespedeza  striata). 

Peanut, — This  family  also  includes  the  peanut  {Arachis 
hypogcea)  (Fig.  128),  licorice  plant  {Glycyrrhiza  glabra),  the 
indigo  plant  {Indigofera  tinctoria)  and  many  other  plants  which 
are  valuable  as  forest  trees,  field  crops,  drug  plants,  etc. 

The  peanut  has  a  peculiar  habit  of  sending  do^\^l  a  long 
flower  stem  to  thrust  tRe  young  seed  into  the  mellow  soil  near 
the  roots.  This  occurs  just  after  pollination.  The  pod  develops 
and  ripens  under  ground.  The  crop  is  grown  for  forage  as;  well 
as  for  the  peanuts  themselves.  There  are  chiefly  two  types  of 
peanuts  commercially  gro^Ti  for  human  use :  the  largo  Virginia 
type  and  the  small  Spanish  type.  The  latter  is  commonly  used 
in  candies,  for  making  peanut  butter,  and  for  extracting  oil. 

The  garden  and  field  crops  are  very  generally  grown  from 
the  seeds,  and  the  production  of  the  commercial  supply  is  a  very 
important  industry.  Great  care  should  be  exercised  to  guar- 
antee seeds  true  to  name  and  free  from  weed  seeds. 


204 


IMPORTANT  FAMILIES  OF  PLANTS 

KOSE    FAMILY    (kOSACE.e) 


This  is  the  most  important  fruit  producing  family  in  the 
plant  kingdom.     The  flowers  are  perfect  and  regular.     There 


Fia.  128.— Peanut  plant  with  the  elongated  stems  sending   seeds   into   the   soil   shown  at 
right  and  left. 

are  usually  five  sepals,  five  petals  and  many  stamens,  but  the 
character  of  the  ovary  is  extremely  variable  in  the  diiferent 
genera.*  The  wild  rose  may  be  taken  as  a  type;  it  possesses  the 
above  characters  and  has  an  inferior  ovary. 


PEACH 


205 


The  apple  {Pyrus  malus)  (Fig.  129)  shows  the  same  gen- 
eral characters,  but  the  ovary  becomes  fleshy  and  shows  a  division 
into  five  well-developed  parts.  It  probably  originated  in  south- 
western Asia  and  adjacent  Europe  and  was  used  by  the  human 
race  in  prehistoric  times. 

The  pear  (P.  communis)  and  the  quince  (P.  crjdonia)  are 
very  similar  in  character  to  the  apple. 


Fig.  129. — Apple,  with  section  showing  structure  of  seed  cases. 

The  peach  (Fruiius  pers-ica)  (Fig.  130)  shows  the  same 
general  character  of  sepals,  petals  and  stamens  as  the  preceding, 
but  the  ovary  is  superior  and  develops  into  a  fleshy  fruit  with 
a  single  hard-shelled  seed.  It  is  undoubtedly  of  Asiatic  origin, 
but  was  carried  into  Europe  by  the  Greeks  and  Romans  at  a 
very  early  date.  It  was  introduced  into  Great  Britain  during 
the  sixteenth  century  and  thence  into  America  about  1680.     It 


206 


IMPORTANT  FAMILIES  OF  PLANTS 


reaches  its  g^-eatest  perfection  in  China  and  in  the  United 
States.  The  almonds  [P.  communis  and  P.  nam)  are  closely 
related  to  the  peach  ;  and  the  nectarines  are  smooth-skinned  vari- 
eties of  the  peach. 

Plums  also  belong  to  the  genus  Prunus  (P.  domesHca — 
Damson  plum)  and  are  also  said  to  be  of  Asiatic  origin,  al- 
though some  botanists  claim  that  they  are  indigenous  to  Europe. 
The  prunes  of  commerce  are  varieties  of  plums  which  are  espe- 


FlG.  130. — Peach,  an  example  of  the  stone  fruits.     The  plum  and  cherry  are  other  examples. 


cially  well  adapted  to  drying.  There  are  also  several  species 
of  American  plums. 

Cherries  also  belong  to  the  genus  Prunus  and  are  well  known 
in  both  Europe  and  America. 

Raspberries,  blackberries  (Fig.  181)  and  dewberries  belong 
to  the  genus  Bulms  of  the  family  Rosacese.  In  most  cases  there 
are  five  petals  and  five  sepals  and  many  stamens  as  in  the  preced- 
ing genera,  but  they  differ  from  the  preceding  in  having  a  num- 
ber of  ovaries  which  ripen  into  the  well-known  aggregate  fruit. 


POLLINATION  OF  STRAWBERRIES  207 

In  the  blackberries  aud  dewberries,  the  receptacle  forms  a  part 
of  the  fruit,  but  in  the  raspberries  the  ovaries  are  separated 
from  the  receptacle. 

Strawberries  (Fig.  132)  belong  to  the  genus  Fragaria  and 
have  flowers  very  similar  to  the  members  of  the  genus  lluhus,  but 


Fio.  131. — Blackberry,  a  form  of  aggregate  fruit. 

fruit  consists  primarily  of  a  large  fleshy  receptacle  carrying 
numerous  naked  akciios  on  its  surface. 

Pollination  of  Strawberries. — The  flowers  of  some  varieties 
of  strawl>erries  have  very  little  or  no  pollen.  The  two  types 
of  blossoms,  with  aud  without  stamens,  arc  shown  in  Fig.  133. 
Growers  are  unable  to  obtain   fruit  from  the  imperfect  va- 


208 


IMPORTANT  FAMILIES  OF  PLANTS 


rieties  (not  having'  pollen)  unless  those  with  perfect  flowers  are 
grown  near  thein.  The  two  types  may  be  planted  together,  with 
at  least  one  row  of  a  perfect-flowered  sort  for  three  or  four  rows 
of  the  imperfect  ones,  and  these  nuist  be  such  as  blossom  at 
the  same  season. 


-   ^ 

■'^ 

^SS^^^ir  'M^ 

•r'^M^ 

jftB^^^M^HBrTji^^ 

''        V^fflWB 

uSmH^j^F^ 

w^^^S^^m 

tL-j^gKS^MKt 

B^^^^hBBB| 

_„ .^Ji 

\ 

,       -    -.^ 

Fig.  132. — Strawberry. 


The  perfect-flowered  varieties  will  produce  fruit  when 
planted  alone.  They  are  more  popular  than  the  others.  Two 
varieties  with  imperfect  flowers  are  Warfield  and  Haverland. 
Crescent  and  Glen  Mary  bear  very  little  pollen.  Over  fifty 
perfect-flowered  varieties  are  known.  Some  of  these  are  Dun- 
lap,  Aroma,  Gandy  and  Excelsior. 


BUDDING  OF  PEACHES  AND  PLUMS  209 

As  the  strawberry  propagates  itself  by  means  of  runners 
which  take  root  at  the  nodes,  the  varieties  are  easily  kept  pure. 
The  crossing  of  the  pollen  does  not  affect  the  character  of  the 
fruit  or  the  purity  of  the  plants  grown  from  the  nmners. 

Poorly  developed  fruits,  called  "  nubbins,"  are  often  the 
result  of  poor  pollination.  This  may  be  due  to  one  of  several 
causes:  (a)  frost,  (b)  hail,  (c)  rain,  (d)  spattering  of  soil  on 
the  pistils,  (e)  insufficient  pollen  on  varieties  blooming  late  in 
the  season.  Mulches  of  straw  or  other  litter  will  prevent  injury 
from  spattering  soil  during  heavy  storms.  Growing  several 
varieties  together  will  aid  in  supplying  enough  vigorous  pollen 
and  cause  better  development 
of  the  fruit. 

Propagation.  —  Apples, 
pears,  and  quinces  are  poma- 
ceous  fruits  and  propagated 
by  growing  stocks  from  seeds, 

thpn      VinrlfliSio'     nnrl      oToffino-  ^i^-     ^33.  —  Flowers    of     strawberriea. 

men      OUaaing     ana     graiting        pi.tiiiate    or   imperfect   at    left.      Perfect   at 

with  the  desired  varieties.  "^^*-  (Productive  Fam-ing.) 
The  seeds  are  obtained  from  the  pomace  of  the  cider  mills.  For 
many  years  it  was  very  generally  believed  that  seeds  and  stocks 
from  France  were  better  than  the  domestic  supply,  but  in  recent 
years  the  sentiment  has  been  changing  and  a  very  important 
stock-growing  industry  has  developed  in  Kansas,  Nebraska, 
Iowa  and  other  states. 

Blackberries,  dewberries  and  raspberries  are  usually  gro^vn 
from  suckers  and  root  cuttings.  jSTew  varieties  are  grown 
from  seed. 

Budding  of  Peaches  and  Plums.— The  steps  in  the  method 
of  shield-budding  are  shown  in  Fig.  134.  The  seeds  are  sprouted 
in  early  spring  after  being  mechanically  cracked,  or  broken  by 
freezing  in  moist  soil.  Scions  are  cut  from  the  cun*ent  season's 
growth  in  August  and  September,  and  the  buds  from  these  are 
14 


210 


IMPORTANT  FAMILIES  OF  PLANTS 


inserted  under  the  bark  of  the  young  seedlings  riglit  away. 
These  buds  remain  dormant  until  spring.  When  growth  begins 
the  seedling  top  is  pruned  away,  leaving  only  the  shoot  of  the 
good  variety. 

For  June  budding,  dormant  buds  are  gathered  in  late  fall 
and  held  until  June  in  wet  sawdust  in  a  cold  cellar  or  in  other 
cold  storage.  The  budding  is  done  in  June  on  seedlings  started 
in  very  early  spring. 

Root  Grafting  of  Apples  and  Pears. — When  trees  are  to  be 


Fig.  134. — Steps  in  budding  the  .stems  of  seedlings  with  buds  of  good  varieties.  A, 
the  shield-shaped  bud  and  parts  cut  from  any  good  variety.  B,  a  T-shaped  cut  made  in 
the  bark  of  the  seedling  stem.  C,  the  same  with  bark  opened.  D,  the  good  bud  set  in 
place  under  bark.  E,  the  wound  well  wrapped  and  tied  with  raffia  or  waxed  cotton. 
(Productive  Farming.) 

propagated  by  root  gTafts  (Fig.  135),  tlie  tongue-grafting  is 
usually  done  in  the  winter.  The  seedlings  of  one  season's 
growth  are  dug  in  the  fall  after  the  leaves  are  off.  They  are 
stored  in  small  bundles  in  boxes  of  wet  sawdust  in  a  cold  cellar. 
The  scions  from  the  desired  varieties  are  gathered  about  the 
same  time.  They  are  labeled  and  stored  in  like  manner.  The 
spare  hours  of  winter  are  used  for  the  work,  which  should  be 
done  in  a  cool  room  or  cellar.  The  materials  and  new  grafts 
must  be  kept  moist  and  cool  during  the  process.  The  grafts 
are  then  stored  in  wet  sand  or  sawdust  in  a  cool  cellar  till  dan- 


GOURD  FAMILY 


211 


ger  of  severe  frost  is  over  in  the  spring.  They  are  then  set  in 
rows  in  good  garden  soil.  They  are  planted  deep  enough  to 
leave  only  one  or  two  buds  above  ground.  Here  they  arq  grown 
for  a  year  or  more  before  being  transplanted  to  the  orchard. 

The  peach,  plum  and  cherry  are  drupaceous  fruits  and  are 
usually  propagated  by  growing  stock  from  seeds  and  then 
budding  or  occasionally  grafting.  Plums  are  sometimes  grown 
from  suckers.  p^        .     ■' 

r\\\      III 

SAXIFRAGE  FAMILY    (SAXIFKAGACE.E  ) 

Herbs  or  shrubs  with  perfect,  reg- 
ular (occasionally  irregular)  flowers. 
Calyx  more  or  less  united  with  the 
ovary,  four  to  five  petals  attached  to 
calyx,  stamens  same  number  as  the 
petals  and  alternate  with  them  or  two 
to  ten  times  as  many.  Ovary  more  or 
less  inferior.  Fruit  a  two-chambered 
capsule  or  true  berry.  Leaves  alter- 
nate or  opposite  or  whorled. 

Currant  and  Gooseberry. — The 
common  red  currant  {Bihcs  ruhruni), 
the  black  currants  (R.  floridum  and 
R.  nigrum),  the  gooseberries  (R.  grossidaria  and  R.  cynosbate), 
the  American  gooseberry  (R.  hirtellum)  and  many  species  and 
varieties  of  currants  and  gooseberries  (Fig.  13G)  are  valuable 
fruits.  They  are  extensively  grown  as  garden  fruits,  but  the 
historical  records  are  very  imperfect  and  uncertain. 

Gooseberries  and  currants  are  usually  ol>tain0d  from  hard- 
wood cuttings,  but  new  varieties  are  grown  from  seed. 

GOURD  FAMILY    (cUCURBITACE.e) 

This  very  important  family  has  monoecious  or  dicrcious,  oc- 
casionally perfect,  usually  solitary  white  or  yellow  flowers  (Fig. 


Fig.  135. — Steps  in  making  the 
tongue-graft  used  in  root  grafting 
apples,  pears,  etc.  A  and  B,  root 
and  scion  with  tongue  cut  in  each. 
C,  the  two  shoved  together  and 
ready  to  be  tied  with  waxed  cotton. 
(Productive  Farming.) 


212 


IMPORTANT  FAMILIES  OF  PLANTS 


Fig.  136.— Gooseberry. 


Fig.  137. — Cucurbit  blossom. 


THE  PUMPKIN,  GOURD,  AND  SQUASH 


213 


137.)  Calyx  five-cleft  and  bell-shaped;  corolla  five-cleft  and 
bell-  or  wheel-shaped;  stamens  five,  ovary  inferior  and  one  to 
many  chambered,  developing  into  a  many-seeded  true  berry 
fruit.  In  many  species  the  fruit  is  large  and  fleshy  and  edible. 
Among  the  most  important  are : 

The   cucumber    {Cucumis   sativus),   which    is   of   Asiatic 
origin  and  was  cultivated  about  three  thousand  years  before 


Fig.  13S.— Uibhed  type  ..f  (.-ant  .1. 


the  Christian  Era.  The  muskmelon  or  cantaloupe  (C.  melo) 
(Fig.  138),  is  indigenous  to  Asia  and  possibly  tO'  Africa. 
It  was  cultivated  by  the  ancient  Egyptians  and  was  known  to 
the  early  Greeks  and  Romans.  The  watermelon  (Citrulhis 
vulgaris)  is  a  native  of  the  torrid  regions  of  Africa,  but  was 
cultivated  long  before  the  Christian  Era.  It  is  now  widely 
distributed  throughout  the  tropical  and  temperate  zones. 
The  pumpkin,  gourd,  and  squash — (CucurhUa  melopepo) 
flat  squash,   (C  verrucosa)   warty  or  long-necked  squash,    (C. 


214 


IMPORTANT  FAMILIES  OF  PLANTS 


maxima)  winter  or  gourd  squash,  (C*.  pepu)  pumpkiu — are 
well-known  products  of  both  tropical  and  temperate  climates. 
The  pumpkin  is  supposed  to  be  of  American  origin. 


Fig.  1.39. — The  long  form  of  carrot. 


The  members  of  this  family  are  very  generally  gi'own  from 
seed  and  are  widely  distributed  througliout  the  temperate  and 
tropicar  climates.     The  growing  of  cucumbers  under  glass  has 


COFFEE  AND  QUININE  215 

developed  into  an  important  industry  near  many  of  our  large 
cities.  The  weed  members  of  this  family  are  of  no  very  great 
importance. 

PARSLEY  FAMILY   (uMBELLIFER^) 

The  family  is  characterized  by  five-parted  calyx  and  cor- 
olla; tvi^o-chambered  inferior  ovary  and  umbel  inflorescence. 
Among  the  most  important  members  are:  The  celery  (Apium 
graveolens),  which  is  well  known.  It  was  used  as  food  by  the 
ancient  Egyptians,  Greeks  and  Romans  and  also  as  a  medicine 
by  the  Egyptians.  The  parsnip  (Pastinaca  saliva)  originated 
in  Europe  but  is  now  widely  cultivated  as  a  food  for  man  and 
live  stock.  The  carrot  {Daucus  carota)  (Fig.  139)  is  a  vege^■ 
table  whose  history  is  not  known. 

This  family  also  includes  the  anise  (Pimpinella  anisum)  ; 
asafoetida  (Ferula  narthex)  ;  coriander  (Coriandrum  sativum)  ; 
parsley  (Carum  petroselinum)  ;  caraway  (Carum  carui)  ;  and 
many  other  more  or  less  well-known  plants,  some  of  which  are 
useful  while  others  are  pests. 

The  members  of  this  family  are  grown  from  the  seed.  Cel- 
ery, parsnips  and  carrots  may  be  kept  in  storage  for  consider- 
able time.  This  family  also  includes  a  number  of  weeds  which 
can  be  kept  in  control  by  the  use  of  cultivated  crops  and  also 
by  the  use  of  cowpeas,  soy  beans  or  similar  smother  crops. 

MADDER    FAMILY    (rUBIACE.Ts) 

Coffee  and  Quinine. — This  family  includes  the  coffee 
{Coffea  arahica  and  C.  Uherlca),  the  quinine  plant  {Cincliona 
officinalis)  and  other  plants  with  interesting  histories.  (Read 
the  history  of  these  plants  in  an  encyclopedia.) 


216 


IMPORTANT  FAMILIES  OF  PLANTS 


SUNFLOWER  OK   COMPOSITE   FAMILY    (cOMPOSITyE) 

This  is  one  of  the  hirgest  families  of  the  flowering  plants. 
It  is  characterized  by  nnmerous  small  flowers  growing  in  a  close 
head.  These  flowers  are  either  polygamous  or  monojcious.  The 
ovary  is  inferior  and  the  calyx  tube  is  attached  to  it ;  the  corolla 
is  five  cleft,  either  tnbnlar  or  strap-shaped ;  stamens  five,  attach- 
ed to  corolla ;  anthers  united  into  a  tube  surrounding  the  two- 
cleft   style.      In  most  plants   the   central   or  disk  flowers  are 


Fig.  140. — Sunflower,  showing  the  composite  flower  head. 

tubular   and    the   marginal   flower   strap-shaped,   but   in   some 
plants  all  of  the  flowers  are  of  the  same  kind. 

This  'family  includes  some  few  plants  used  for  food,  such 
as  the  Jerusalem  artichoke  (Helianthus  tuherosus  L. ),  lettuce 
(Lactuca  sativa),  some  few  others  that  are  used  in  medicines, 
and  a  large  number  that  are  used  for  ornamental  purposes, 
such  as  the  sunflower  {Helianthus  annuus)  (Fig.  140),  the 
daisy  and  chrysanthemum  (Chrysanthemum  carineum),  gold- 
enrods  (Solidagos),  asters,  dahlias  and  others. 


BLUEBERRY,   HUCKLEBERRY  AND  CRANBERRY         217 

This  family  also  includes  the  dandelion  (Taraxacum 
officinale),  iron  weed  {Vernonia),  fleabanc  and  meadow  white 
tap  (Erigeron),  thistle  (Carduus),  and  many  others  that  are 
troublesome  as  weeds. 

HEATH    FAINIILY     ( VACCINIACE.e) 

The  flowers  of  this  very  interesting  family  are  four  to  five 
parted ;  calyx  attached  to  am  inferior  ovary,  the  petals  united ; 


Fig.  141. — Cranberries. 

stamens  eight  to  ten ;  ovary  of  several  chambers  and  developing 
into  a  true  berry. 

Blueberry,  Huckleberry  and  Cranberry. — The  most  im- 
portant plants  of  this  family  are  the  blueberries  and  huckleber- 
ries {Gaylussacia)  and  the  cranberries  (Oxycoccus)  (Fig. 
141),  both  of  which  are  indigenous  to  America. 

Cranberry-growing  is  a  highly  specialized  industry  which  is 


218  IMPORTANT  FAMILIES  OF  PLANTS 

restricted  to  very  limited,  parts  of  the  country.  The  conditions 
for  success  in  this  line  of  farming  are  to  be  found  in  very  few 
parts  of  the  country.  Old  peat  bogs  with  an  ample  supply  oi 
water  are  essential. 

CONVOLVULUS  FAMILY  (CONVOLVULACE^) 

The  flowers  of  this  family  are  perfect  and  terminal ;  calyx 
five-cleft  and  persistent;  corolla,  funnel-shaped  and  five-cleft; 
stamens  five  and  attached  to  the  corolla.  The  family  contains 
a  large  number  of  ornamental  plants  of  which  the  morning 
glory  is  typical.  Many  of  these  plants  are  so  common  as  to 
be  wTcd  pests. 

Sweet  Potato. — The  most  important  economic  member  of 
this  family  is  the  sweet  potato  {Ipoma'a  batatas).  Some  au- 
thorities claim  that  this  plant  is  Asiatic,  while  others  claim 
that  it  is  American.  It  may  possibly  be  indigenous  to  both 
continents.  It  reaches  its  greatest  development  in  the  tropical 
countries,  where  it  makes  a  very  luxuriant  growth  and  blooms 
freely,  but  it  is  extensively  cultivated  in  the  sandy  districts 
of  the  temperate  zones.  Certain  varieties  are  cultivated  un- 
der the  name  of  yams,  but  the  true  yam  belongs  to  the  family 
Dioscoreacea\ 

Propagation. — In  the  temperate  zone,  sweet  potato  plants 
are  grow^n  from  roots  which  are  laid  in  hot-beds,  cold-frames 
or  forcing  houses,  dependent  upon  the  climatic  conditions.  The 
plants  are  then  transferred  to  the  field  and  are  most  productive 
in  sandy  soil.  In  tropical  countries,  the  crops  are  usually  grown 
from  cuttings  set  directly  in  the  field.  This  family  includes 
a  number  of  very  troublesome  weeds,  which  are  difficult  to 
eradicate  except  by  the  use  of  cowpeas,  soy  beans  or  similar 
smother  crops. 

This  family  also  includes  the  dodder  or  love  vine,  which 
we  find  growing  parasitically  on  many  of  our  flowering  plants. 


POTATO  219 

The  seeds  germinate  in  the  soil,  but  the  vine  very  soon  attaches 
itself  to  another  plant  and  loses  its  connection  with  the  soil, 
thus  becoming  strictly  parasitic.  Some  of  the  dodders  are  very 
troublesome  weeds. 

NIGHTSHADE    FAMILY    (sOLANACEzE) 

This  is  one  of  the  most  important  families  in  the  plant  king- 
dom.    The  calyx  is  five-cleft   (occasionally  four  or  six)   and 


Fig.  142. — Blossom  of  egg-plant.     Note  its  similarity  to  the  Irish  potato  blossom. 

persistent;  corolla  five-cleft  (sometimes  so  deeply  that  the  petals 
appear  to  be  distinct)  ;  stamens  five  and  attached  to  the  corolla; 
ovary  two-  to  five-chambered  and  with  many  ovules.  (Fig.  142.) 
Fruit  varying  from  a  dry  pod  to  a  true  fleshy  berry.  The  most 
important  members  of  this  family  are: 

The  potato  (Solanum  tuberosum)  is  indigenous  to  Chile, 
Peru  and  Equador,  where  it  was  found  growing  by  the  early 
Spanish  explorers.  It  is  now  widely  distributed  throughout 
the  world  and  is  one  of  our  most  important  food  products.  The 
wild  potatoes  produce  small  tubers  and  many  seeds,  but  careful 


220  IMPORTANT  FAMILIES  OF  PLANTS 

selection  has  given  us  many  varieties  witli  large  tubers  and  few 
or  no  seeds. 

The  tomato  {Ly  coper  si  cum  esculeii{u)n)  (Fig,  143)  is  a 
native  of  Central  and  South  America  and  is  said  to  have  been 
cultivated  by  the  ancient  inhabitants  of  Mexico.  Its  uses  are 
well  known. 

The  pepper  {Capi-icuin  annuum)   (Fig.  144)   (rod  pepper. 


Fig.  143. — Tomatoes. 

C.  fastigiatum  and  C.  fructescens,  Cayenne  pepper,  and  C. 
grossum,  bell  pepper)  is  also  indigenous  to  tro})ical  and  sub- 
tropical America.     The  uses  are  well  known. 

Tobacco  (Nicodcoiu  tahacum)  is  another  well-known  Amer- 
ican plant  which  is  now  cultivated  in  many  parts  of  the  world. 

This  family  also  includes  the  deadly  nightshade  (Atropa 
helladonna)  from  which  certain  important  drugs  are  obtained, 
the  common  black  nightshade  (Solanum  nigrum),  and  many 
other  interesting  plants. 


GOOSEFOOT  FAMILY 


221 


Propagation. — It  is  well  known  that  the  potato  is  grown 
from  the  tnbers,  but  the  other  cnltivated  members  of  this'fam- 
ily  are  very  generally  gi'owu  from  seeds.'  The  seedlings  are  read- 


FiG.  144. — -The  sweet  pepper. 

ily  transplanted.     This  family  also  contains  a  few  tronblosome 
weeds  which  can  iisnally  be  controlled  by  smother  cro})*. 

goosi<:foot  faafily  (cii exopodiace.k") 
The  members  of   ,]iis  family  are  very  widely  distribnted. 
They  are  mostly  herbaceons  with  alternate  leaves ;  flowers  small, 
greenish,  in  spikes  or  beads,  usually  regular ;  no  corolla ;  calyx 


222  IMPORTANT  FAMILIES  OF  PLANTS 

three  to  five  lobcd  (rarely  one  or  no  sepals)  ;  stamens  as  many 
as  lobes  of  calyx  or  fewer;  pistil  one  with  one  chamber;  frnit 
one-seeded  in  a  loose  bladdery  capsule  or  utricle. 

Beets,  Spinach  and  Swiss  Chard. — This  family  includes 
the  common  beet  (Beta  vulgaris)  (Fig.  145),  which  is  indigen- 
ous to  both  Europe  and  Asia  and  was  used  for  five  hundred 

years  or  more  before  the 
Christian  Era.  Some  varied- 
ties  are  extensively  used  as  a 
table  vegetable,  others  for 
stock  feed  and  still  others  for 
the  manufacture  of  sugar. 
The  spinach  is  an  Asiatic 
plant  which  has  been  culti- 
vated and  used  from  un- 
know^l  time.  The  Swiss 
chard,  which  is  so  extensively 
used  as  a  salad,  is  a  variety 
of  the  common  l>eet. 

BUCKWHEAT    FAMILY 
(POLYGONACE.I:) 

Buckwheat. — This  fam- 
ily includes  the  buckwheat 
(F ago pyrum    escidenfum ) 

Fig.  145.-The  table  beet.  ^-p-^^    ^^^^^    ^^  ^^.^^.^  p^.^^^^ 

which  is  well  known.  It  was  at  one  time  kno\ni  as  beech  wheat, 
owing  to  the  resemblance  of  the  seed  to  that  of  the  beech,  but 
this  was  gradually  modified  to  "  buckwheat." 

Rhubarb. — This  family  also  includes  the  well-known  vege- 
table, rhubarb  or  pie-plant  (Rheum  rhajwnticum),  which  is  of 
East  European  or  West  Asiatic  origin. 

Buckwheat  is  grown  from  seed.     Rhubarb  may  be  grown 


MULBERRY 


223 


from  the  seed,  but  will  not  come  true  to  type  and  requires 
three  years  to  come  to  maturity.  It  is  much  better  to  secure  new 
plants  by  dividing  the  crowns.  This  family  includes  many 
important  weeds;  among  the  most  troublesome  is  the  sorrel, 
which  grows  in  great  abundance  in  sour  (acid)   soil.     It  can 


Fig.  146. — Buckwheat. 

be  eradicated  by  heavy  applications  of  lime  and  the  use  of 
legume  crops.     The  docks  are  also  members  of  this  family. 

NETTLE    FAMILY     (URTICACE^) 

This  family  contains  herbs,  shrubs  and  trees  and  includes 
some  very  important  plants.  Flowers  monoecious,  dioecious  or 
rarely  with  perfect  flowers ;  calyx  regular ;  stamens  as  many 
as  the  tubes  of  the  calyx  or  fewer  and  opposite  them;  pistil 
one  with  two  cells. 

The  mulberry  (Morus  rubra,  American  red  mulberry,  and 
.V.  alba,  Asiatic  white  mulberry)  is  well  known.     The  flowers 


224 


IMPORTANT  FAMILIES  OF  PLANTS 


are  unisexual  and  the  plants  are  usually  monoecious.  Both 
male  and  female  flowers  are  borne  on  short  spikes  and  have  a 
four-parted  perianth  or  calyx.  The  white  mulberry  was  intro- 
duced into  Europe  about  the  middle  of  the  fifteenth  century, 
into  Mexico  by  Cortez  in  1522  and  into  Virginia  by  James  I 


Fig.  147— Fig. 


in  1619.  It  is  extensively  grown  in  China  for  the  feeding  of  the 
silk  worm.  The  American  mulberry  produces  a  very  good  fruit 
and  the  wood  is  very  durable  and  seiwiceable  for  many  purposes. 
The  elms  (Ulmus  Americana,  American  or  white  elm; 
U.  fulva,  slippery  or  red  elm;  U.  racemosa,  corky  elm)  are 
among  our  most  valuable  shade  and  ornamental  trees. 


HICKORIES  225 

The  common  hop  (Hutnulus  lupulus)  is  well  known.  It 
is  used  in  makini;  yeast,  beer  and  medicine. 

Fig  and  Rubber. — The  genus  Ficus  includes  the  common 
fig  {Ficus  carica)  (Fig.  147),  the  India  rubber  tree  {F.  elas- 
tica)  and  the  banyan  tree  {F.  bengalensis). 

The  hemp  {Canimbis  sativa)  also  belongs  to  this  family. 

Propagation. — The  mulberry  is  usually  grown  from  root 
cuttings,  or  from  layerings,  or  by  budding.  New  varieties  are 
obtained  from  seeds.  The  elms  are  usually  grown  from  seeds 
which  mature  very  early  in  the  spring  and  are  sown  at  once, 
but  may  also  be  grown  by  layering  or  by  grafting.  Hops  may 
be  grown  from  seeds,  from  divisions  or  from  hard  wood  cut- 
tings. Hemp  is  grown  from  seed  and  is  one  of  the  very  im- 
portant fibre  plants. 

WALNUT    FAMILY    ( JUGLANDACE.e) 

This  very  important  family  contains  two  valuable  groups  of 
trees,  the  walnut  and  the  hickory.  The  flowers  are  monoecious. 
The  staminate  flowers  are  usually  borne  in  catkins  and  each 
consists  of  a  six-lobed  (occasionally  two^  or  three-lobed)  peri- 
anth and  from  six  to  forty  stamens.  The  pistillate  flowers  are 
terminal  and  may  be  solitary,  few  or  clustered ;  the  calyx  tube 
is  four-toothed  and  styles  two  in  number.  The  fmit  is  a  dru- 
paceous nut. 

Walnuts, — The  American  black  walnut  (Juglans  nigra)  is 
well  known  both  for  the  nuts  and  for  the  high  quality  of  the 
wood.  The  American  butter-nut  (/.  cinerea)  produces  an  ex- 
cellent nut,  but  the  wood  is  not  so  valuable  as  that  of  the  black 
walnut.  The  so-called  English  walnut  (</.  regia),  which  is  now 
extensively  cultivated  in  many  parts  of  the  world,  is  of  Asiatic 
origin.    It  is  of  great  value  both  for  nuts  and  lumber. 

Hickories. — The  various  species  of  hickory  {Hicoria  ovata, 
15 


226 


IMPORTANT  FAMILIES  OF  PLANTS 


shell  bark,  and  //.  olivcuforinis,  11.  pecan,  the  pecan  of  com- 
merce) are  well  known  for  their  nuts  and  useful  woods. 

Propagation. — The  members  of  this  family  can  be  grown 
from  seeds  or  by  grafting.  The  fact  that  seedlings  are  subject 
to  more  or  less  variation  makes  it  necessary  to  perpetuate  de- 
sirable varieties  by  grafting,  which  must  be  done  with  consid- 
erable care  in  order  to  be  successful. 


FlQ.  148. — Pecan  nuts,  showing  one  of  tho  many  forms  grown  for  market.     (U.  S.  D.  A.) 


OAK    FAMILY     (CUPULIFER^) 

This  family  is  similar  to  the  preceding.  The  flowers  are 
monoecious.  The  staminate  flowers  in  catkins,  calyx  five-parted 
(occasionally  five  to  twelve),  stamens  two  to  twenty.  The  pis- 
tillate flowers  terminal,  six-parted,  and  attached  to  the  two-  to 
seven-chambered  ovary.  Fruit  a  one-seeded  nut.  This  family 
includes  the  oaks,  chestnut,  hazelnuts,  beech,  and  others. 

There  are  many  species  of  oaks  (Quercus)  which  are  among 


BANANA  FAMILY 


227 


the  most  important  of  our  forest  trees.  The  hazehmts  {Corij- 
liLs)  and  the  chestnuts  {Castanea)  are  highly  prized  for  their 
edible  nuts. 

Feed  for  Swine. — The  nuts  of  the  trees  of  this  family  and 
the  preceding  one  are  abundantly  used  in  feeding  swine.  The 
animals  are  allowed  to  gather  the  acorns  and  nuts  (called  mast) 
from  the  ground  under  the  trees,  during  the  fall  and  winter  days 
when  there  is  no  snow  on  the  ground.  The  flesh  produced  from 
mast  is  often  of  good  quality,  and  the  economy  of  its  produc- 
tion is  readily  understood.  Beechnuts 
alone  produce  a  soft  flesh,  and  some 
com  or  other  grain  is  fed  for  a  few 
weeks  before  slaughtering. 

WILLOW    FAMILY    (sALICACEiE) 

In  this  family,  both  the  staminate 
and  pistillate  flow^ers  are  borne  in  cat- 
kins. It  includes  the  willows  (Salix), 
the  poplars,  and  the  cottonwoods 
{Populus). 

All  members  of  this  family  grow         Fig.  149.— Bur  of  native  chest- 

^  nut  showing  two  seeds  within.  ("Pro- 

readily    from    cuttings    and    can   be  ductive  Plant  Husbandry."^ 


growm  from  gTafts.    The  poplars  anc 
gro%\ai  from  seed. 


cottonwoods  are  frequently 


BANANA    FAMILY    (ziNGIBREACE^) 

This  very  important  family  includes  a  number  of  inter- 
esting families  of  which  the  banana  of  commerce  (Musca  para- 
disiaca)  is  an  example.  Another  species  of  the  banana  (M. 
textilis)  produces  a  fibre  from  which  the  ]\ranila  hemp  is 
manufactured. 

The  edible  baiumas  are  grown  from  suckers,  but  the  fibre 
varieties  are  grown  from  seeds. 


228  IMPORTANT  FAMILIES  OF  PLANTS 

LILY    FAMILY    (lILIACE/E) 

This  very  large  and  interesting  family  contains  many  valu- 
able plants.  The  flowers  arc  perfect,  usually  terminal  and 
solitary  but  occasionally  in  racemes  or  spikes.  The  perianth 
is  more  or  less  tubular  and  six-parted  or  united  into  six  lobes ; 
six  stamens  and  a  three-chambered,  many-seeded  superior 
ovary. 

Lily,  Asparagus,  Onion. — This  family  may  be  character- 
ized by  the  many  species  of  lilies  which  grow  wild  or  are  culti- 
vated for  ornamental  purposes. 

Among  other  important  vegetable  plants  of  this  family  are 
the  asparagus  (Asparagus  officimiUs)  and  the  onion  {AUiam 
cepa  and  A.  fistulosum).  Among  the  ornamental  plants  are 
the  many  true  lilies,  tulips,  hyacinths,  lilies  of  the  valley,  etc. 

Some  Bad  Weeds. — The  family  includes  a  large  number 
of  uncultivated  plants,  some  of  which  are  troublesome  weeds. 
Among  the  most  important  of  these  weeds  are  the  wild  onions, 
or  wild  garlic,  which  frequently  becomes  established  in  old  pas- 
tures and  gives  a  peculiar  odor  to  milk  and  butter  from  cows 
that  feed  on  it.  It  is  very  difficult  to  eradicate,  but  can  be 
done  by  shallow  plowing  just  deep,  enough  to  expose  the  bulbs 
to  the  sun,  followed  by  the  growing  of  well-cultivated  crops. 

Propagation. — The  asparagus  is  usually  grown  from  seed, 
but  old  crowns  are  sometimes  divided.  Onions  are  grown  from 
seeds,  sets  and  bulbs.  The  ornamentals  are  usually  grown  from 
bulbs  or  seeds. 

GRASS    FAMILY    (gRAMINE^Ts) 

Annuals  or  perennials,  frequently  with  fibrous  or  creeping 
rhizomes  and  often  stoloniferous  at  the  lower  nodes.  Flowers 
perfect  (occasionally  monopcious  or  diopcious  or  polygamous) 
and  borne  in  spikelets  which  are  collected  into  spikes  or  panicles. 
Perianth  imperfect  (occasionally  wanting)  membranous  or 
fleshy.     Stamens  three  or  six  (occasionally  four,  two  or  one). 


WHEAT 


229 


Ovary  superior  with  one  chamber  and  one  ovule  and  sur- 
mounted by  two  (occasionally  three)  styles.  Stems  cylindrical 
(occasionally  flattened),  tubular  (occasionally  hollow).  Leaves 
alternate,  in  two  ranks,  springing  from  the  nodes,  petioles 
sheathing  the  stems.  This  very  large  family  contains  our  grains 
and  grasses  (Fig.  5,5). 

Wheat  {Triticum  vulgare  and  varieties)  is  the  well-known 

i||||«W 

lilin 

r--  '  '  '  i 

Fig.  150.— Six  types  of  vvhoat.     Top  row,  flunini,  Polisli  wheat,  and  white  winter.    Bottom 
row,  red  winter,  hard  winter,  and  harti  «i)rinK.     ("Productive  Farm  Crops.") 

bread  plant  of  the  temperate  zones.  The  spikelets  bearing 
from  two  to  many  flowers  are  arranged  in  a  firm  spike.  The 
little  flowers  are  arranged  in  two  rows  and  protected  by  glumes 
which  sometimes  bear  awns  or  bristles;  three  stamens  and  two 
plum-like  stigmas.  The  fruits  (i.  e.,  grain  enclosed  in  ovary 
coats)  are  about  one-quarter  of  an  inch  in  lengili,  oval,  flattened 
and  grooved  on  one  side.    Some  varieties  are  sowed  in  the  early 


230  IMPORTANT  FAMILIES  OF  PLANTS 

spring  and  han^ested  during'  the  siunnier  and'  known  as  "  spring 
wheat."  Other  varieties  are  sowed  in  the  fall  and  harvested 
the  following  July  and  known  as  "  winter  wheat."  Wheat 
probably  originated  in  western  Asia  and  was  cultivated  long- 
before  we  have  any  authentic  historical  records,     (Fig.  150.) 

Rye  (Secale  cereal e)  is  very  similar  to  wheat  and  is  used  as 
food  for  both  man  and  beast.  We  have  no  satisfactory  records 
telling  us  where  it  was  first  cultivated  by  mankind.     (Fig.  56.) 

Barley  (Hordeum  vulgare,  H.  distichum,  H.  hexastichon 
and  //.  Z eocriton)  is  also  similar  to  wheat  and  is  also  used  for 
man  and  beast.  Its  cultivation  probably  antedates  historical 
records. 

Oats  (Avena  sativa)  have  the  two-  to  five-flow^ered  spike- 
lets  borne  in  panicles.  The  glumes  are  membranous  and  with- 
out awns ;  three  stamens  and  two  stiginas.  Annuals  which  are 
sowed  in  the  spring  and  harvested  in  July  or  August.  Its  geo- 
graphical range  is  not  so  great  as  most  of  the  other  cereals ;  it 
grows  well  in  cold  regions  and  rather  poorly  in  warm  countries. 
It  probably  originated  in  western  Asia  and  eastern  Europe, 
but  we  have  no  very  satisfactory  records  of  its  early  cultiva- 
tion and  uses.  Although  it  is  less  nutritive  than  wheat  or  rye 
it  is  very  extensively  used  as  food  for  man  and  beast. 

Millet  (Setaria  itaUca)  is  an  Asiatic  plant  cultivated  many 
centuries  before  the  Christian  Era.  It  is  very  widely  but  not 
extensively  grown  through  many  temperate  and  tropical  coun- 
tries. It  is  very  inferior  to  oats  and  many  other  forage  crops 
wliieli  can  be  grown  with  no  greater  expense  of  time  and  labor. 

Rice  (Oryza  sativa  and  other  species)  is  an  important  trop- 
ical and  subtropical  plant  growing  in  low,  wet  lands.  We  have 
no  definite  records  telling  us  when  it  first  became  the  food  of 
man,  but  it  was  cultivated  for  at  least  2800  years  before  the 
Christian  Era  and  has  probably  contributed  more  food  to  the 
human  race  than  any  other  food  plant. 


CORN 


231 


Com  (Zea  Mays)  (Fig.  151)  is  not  typical  of  the  grass 
family;  the  stem  is  solid  and  the  flower  is  imperfect  and  mo- 
noecious. The  staminate  flowers  are  borne  in  two-flowered  spike- 
lets  which  are  in  turn  borne  on  the  long  spikes  constituting  the 
tassel;  the  pistillate  flowers  are  borne  on  a  large  spike  (cob), 
each  having  a  long,  delicate,  thread-like  pistil  (silk)  and  the 
entire  ear  enclosetl   in  the  large  bracts   (husks).      The  fniit 


Fig.  151. — Corn  showing  both  pistillate  and  staminate  flowers. 

consists  of  the  grain  inclosed  in  the  ovary ;  many  of  these  fruits 
are  arranged  in  rows  on  the  cob  and  constitute  the  ear.  This 
very  important  plant  undoubtedly  originated  in  America  and 
w^as  first  introduced  into  Europe  by  Columbus  in  1520.  It  is 
now  extensively  cultivated  in  temperate  and  tropical  countries. 
There  are  a  great  many  varieties  of  corn,  but  they  are  usu- 
ally classified  in  six  groups  as  follows:  (1)  the  pod  corns,  in 
which  each  grain  has  a  peculiar  shuck  covering,  (2)  the  pop 


232  IMrORTANT  FAMILIES  OF  PLANTS 

corns,  (3j  the  Hint  corns,  (4)  the  deut  corns,  (5)  the  soft  corns, 
and  (0)  the  sugar  corns. 

Sugar  cane  (Saccharum  officinarum)  is  the  well-known 
tropical  and  subtropical  plant  from  which  the  greater  part  of 
our  sugar  of  commerce  is  derived.  It  is  au  Asiatic  plant,  but 
there  are  no  satisfactory  records  concerning  its  early 
cultivation. 

Broom  Com  {^Sorghuui  saccharatuin). — This  is  an  African 
J)] ant  Avhich  is  grown  in  the  United  States  for  the  manufacture 
of  brooms  and  for  stock  feed. 

QUESTIONS 

1.  What  are  the  distinguisliing  characters  of  the  families  Crucifersp, 
Leguminoseae,  Rosaceae,  Cucurbitaceae,  Convolviilaceae,  Solanaceae,  Juglan- 
daceae,  Cupulifera,  Solanaceae,  Liliaceae  and  Graminacse. 

2.  (a)   Make  a  list  of  grain-producing  plants. 
(&)   Give  the  origin  of  each. 

(c)  Give  the  present  range  of  each. 

(d)  Give  the  uses  of  each. 

(e)  Give   the    valuation    of    each. 

3.  (a)  Make  a  list  of  the  fibre-producing  plants. 
(6)  Give  the  origin   of  each. 

(c)  Give  the  present  range  of  each. 

(rf)  Give  the  usesi  of  each. 

(p)  Give  the  valuation   of   each. 

4.  (a)  Make   a    list   of    the    fruit-producing    plants. 

(b)  Give  the  origin  of  each. 

(c)  Give  the  present  range  of  each. 
{d)   Give  the  uses  of  each. 

(e)   Gi\-«  the  valuation  of  each. 

5.  (a)   Make  a  list  of  vegetable  plants. 
(6)   Give  the  origin  of  each. 

(c)  Give  the  present  range  of  each. 

(d)  Give  the  uses  of  each. 

(e)  Give  the  valuation   of  each. 

6.  (a)   Make  a  list  of  luml)er  trees. 
(6)   Give  the  origin  of  each. 

{c)   Give  the  present  range  of  each. 

{d)   Give  the  uses  of  each. 

(c)   Give  the  valuation  of  each. 


QUESTIONS  233 

7.  Make  a  listl  of  agricultural   plants  wliitli   are  of  American  origin. 
Tell  something  about  their  present  range  and  uses. 

8.  Give  an  example  of  symbiosis. 
"J.  Tell  how  legumes  improve  soils. 

10.  Describe  the  propagation  of  the  apple  by  root  grafting. 

11.  Describe  the  budding  of  peaches  and  plums. 

12.  How    and    when    are    stocks    and    scions    grown,  gathered,    stored, 
and  used  ? 

13.  What  are  some  of  the  pollination  problems  with  strawberries? 

14.  Mention  the  different  types  of  cabbages;   of  turnips. 

15.  Describe  the  peculiar  seed-bearing  liabits  of  the  peanut  plant. 


CHAPTER  XXII 

SPECIAL  EXERCISES  WITH  IMPORTANT  FAMILIES 
OF  PLANTS 

Note  to  the  Teacher. — This  outline  is  intended  to  be 
very  brief  and  to  serve  as  an  outline  for  further  reading  in 
various  books  which  should  be  in  the  study-room  or  laboratory. 
The  exercises  are  also  brief  and  may  be  expanded  as  circum- 
stances may  demand.  They  may  be  taken  in  any  order  to  suit 
the  convenience  of  the  teacher.  Other  exercises  may  be  added 
to  the  list  or  substituted. 

1.  The  Lily  and  Its  Relatives. — Dissect  and  study  the 
flower  of  the  lily.  Make  a  series  of  drawings  to  show  the  shapes 
of  the  parts  and  i-elations  one  to  another. 

Study  flower  of  amarillis,  iris,  onion  and  other  similar 
plants  and  compare  with  the  lily. 

2.  Mustard  or  Radish. — Select  a  mustard,  radish  or  any 
other  cruciferous  plant  in  full  bloom.  Note  the  differences  in 
the  leaves,  in  the  different  parts  of  the  plant  from  base  to  tips. 
Make  drawings  of  a  few  typical  specimens. 

Dissect  the  flower,  make  drawings  of  the  different  parts  and 
a  diagram  showing  the  number  and  arrangement  of  the  parts. 
The  character  of  the  ovary  can  be  best  studied  from  seed  pods 
near  maturity. 

Examine  the  seeds  and  make  drawings. 

Examine  the  roots  and  make  drawings.  Compare  with 
the  roots  of  other  cruciferous  plants. 

How  long  from  seed  planting  to  maturity  of  a  new  crop 
of  seeds  ?    Is  this  the  same  for  all  crucifers  ? 

!^^ake  a  list  of  food  plants  belonging  to  this  family.  Make 
a  list  of  native  weeds,  belonging  to  this  family. 

8.  Maple. — The  flowers  of  the  maple  open  very  early ;  some 
234 


OAK,  HICKORY  OR  WALNUT  235 

of  them  are  in  bloom  long  before  the  snow  and  ice  have 
disappeared. 

Study  the  flowers  carefully,  using  a  small  hand  lens.  Make 
drawings  and  diagrams  showing  the  shape  and  arrangement  of 
parts. 

Examine  flowers  from  different  trees.  Do  they  all  show 
both  stamens  and  pistils  ?  Make  a  record  of  the  date  of  the 
blooming  and  of  the  appearance  of  the  leaves. 

Follow  the  development  of  the  seeds  throughout  the  season. 

Make  drawings  and  measurements  of  the  leaves  and  seeds 
from  time  to  time  until  maturity. 

Make  a  list  of  the  maples  in  the  vicinity.  Make  a  list  of 
their  uses. 

4.  Gooseberry  or  Currant, — Dissect  the  flowers  of  one  or 
both  and  make  drawings  to  show  the  shape  and  arrangement 
of  the  parts. 

Make  drawings  of  fruits.  Tell  what  parts  of  the  flower  go 
to  form  the  fruit, 

5.  Cucurbits. — Examine  the  flowers  of  cucumber,  melon  or 
pumpkins.  Make  drawings  of  parts  and  diagrams  to  show  the 
arrangements. 

What  parts  go  to  make  up  the  fruits  1 

6.  Composite. — Study  one  or  more  composite  flowers  such 
as  daisy,  sunflower,  or  dandelion.  Note  the  inflorescence  or 
arrangement  of  the  flowers  in  the  head. 

Examine  flowers  from  the  margin  and  centre  of  the  head. 
Make  series  of  drawings  and  diagrams  to  show  parts  and  ar- 
rangement of  the  individual  flower. 

Make  list  of  useful  composite  plants. 

Make'  list  of  weeds  belonging  to  Compositse. 

7.  Oak,  Hickory  or  Walnut. — Collect,  examine  and  make 
drawings  of  both  staminato  and  pistillate  flowers. 

Compare  with  willow. 


236  SPECIAL  EXERCISES 

S.  Willow. — Collect,  examine  and  make  drawings  of  both 
staminate  and  pistillate  flowers.  Compare  with  oak  or  hickory 
or  walnut. 

9.  Corn  Kernel. — Select  good  grains  of  several  different 
kinds  of  corn,  such  as  flint,  soft,  pop,  and  sweet  corn. 

Make  drawings  and  write  descriptions  of  each.     (Fig.  1.) 

Soak  the  grains  in  hot  water  for  15  minutes.  Cut  each 
grain  longitudinally  and  note  the  following:  hull,  endosperm 
(hard  and  soft  starch),  germ  (scutellum,  plumule,  radicle)  tip 
cap.     (Figs.  1  aiid  4.) 

Compare,  make  drawings  and  write  descriptions  of  each. 

Cut  another  lot  of  grains  in  cross  section ;  make  drawings 
and  write  descriptions. 

Write  a  brief  discussion  of  the  uses  and  value  of  each  of 
the  varieties  used. 

10.  Corn  Seedling. — Germinate  a  few  grains  of  corn  be- 
tween layers  of  wet  filter  paper. 

Examine  newly  germinated  seed  and  others  that  have  been 
germinated  for  several  days.  Note  the  plumule,  radicle,  pri- 
mary and  secondary  roots  and  root-hairs.  Make  drawings  and 
write  descriptions.     (Fig.  4.) 

Carefully  lift  seedlings  that  have  been  growing  in  fine, 
moist  soil.  Why  does  the  soil  cling  to  the  roots  ?  Wash  gently 
and  examine  the  root  system. 

What  does  the  plant  obtain  from  the  soil  ? 

11.  Large  Corn  Plant. — Examine  a  full-sized  corn  plant. 
Note  the  nodes  and  internodes.  How  many  rows  of  leaves  ? 
Where  are  they  attached  ? 

Note  the  sheath  and  blade  of  the  leaf.  Is  the  leaf  parallel 
or  net-veined? 

Note  the  brace  roots  near  the  base  of  the  plant. 

Wliere  is  the  ear  borne  ? 

What  part  is  borne  at  the  top  of  the  plant  ? 


BEAN  OR  PEA  237 

Cut  the  stalk ;  examine  and  describe  its  structure. 

12.  Corn  Flowers. — Where  are  the  corn  flowers  located^ 
Make  a  drawing  of  the  tassel.  Make  a  drawing  showing  one 
pair  of  spikelets  in  place.  Separate  the  parts  of  a  pair  of 
spikelcts.  Make  drawings  of  parts  and  drawing  to  show  their 
position. 

Make  a  drawing  of  a  .young  ear  in  silk.  The  husks  are  bracts. 
Remove  the  husks  from  one  side.     Make  drawing  and  show  the 

What  do  the  grains   and 
silks  correspond  to  in  other  flowers  ? 

Explain  pollination  in  the  corn  flower. 

13.  Wheat  Kernel  and  Its  Germination. — Examine  a  grain 
of  wheat  and  compare  it  with  a  grain  of  corn. 

Make  germination  studies  the  same  as  in  corn. 

14.  Wheat  Plant  and  Flower. — ^Compare  a  stalk  of  wheat 
with  a  stalk  of  corn. 

Where  are  the  flowers  located  'i  Make  a  drawing  of  a  head 
of  wheat.  Remove  a  numbei*  of  spikelets  and  make  a  drawing 
to  show  their  attachment.  Dissect  a  spikelet  and  show  the  fol- 
lowing parts:  Glumes,  i)alea,  stamens,  ovary  and  stigmas. 
Make  drawings  of  each  part  and  drawing  to  show  their  relation 
to  each  other. 

15.  Oats. — Repeat  the  preceding  exercise,  using  oats  in- 
stead of  wheat. 

IG.  Bean  or  Pea.- — ^Make  a  drawing  of  the  leaf  and  label 
all  parts.    If  the  ])lant  is  a  climber  explain  method  of  climbing. 

Dissect  the  flower.  How  many  sepals  ?  Make  drawings. 
(Fig.  47.)' 

ISTote  that  there  is  one  large  petal  or  standard,  two  smaller 
petals  or  laterals  and  two  others  which  fonn  the  keel.  Make 
drawings  of  each  and  diagram  to  show  the  arrangement. 

How  many  stamens  and  what  is  their  arrangement?  Make 
drawing. 


238  SPECIAL  EXERCISES 

How  many  pistils  ?     Make  drawing  and  show  the  parts. 
What  is  its  relation  to  the  stamens  ? 

Make  drawing  of  pod,  showing  both  outside  and  inside. 
(Fig.  47.) 

17.  Bean  and  Pea. — Examine  as  many  other  beans  and 
peas  as  circumstances  will  permit.  Compare  the  leaves, 
method  of  climbing,  flowers  and  seed  pods. 

18.  Bean  and  Pea  Seedlings. — lieview  your  studies  on  the 
bean. 

Plant  a  number  of  beans  and  peas.  Note  the  methods  of 
germination  and  compare  the  seedlings  from  time  to  time  for 
a  period  of  two  or  three  weeks.     Make  drawings. 

19.  Purity  Test  for  Clover  Seeds. — Collect  a  number  of 
samples  of  clover  seeds.     One  ounce  of  each  is  sufticient. 

Weigh  out  two  or  three  grains  of  each  very  carefully.  (Be 
sure  to  use  an  accurate  set  of  balances  such  as  you  will  find  in 
the  physical  and  chemical  laboratories.) 

Spread  this  sample  on  a  sheet  of  white  paper.  Examine 
through  a  large  lens  or  reading  glass  and  remove  (1)  weed 
seeds,  (2)  grass  and  other  varieties  of  clover  seed,  (3)  dirt  and 
other  inert  material.  Weigh,  and  make  and  fill  the  following 
table  in  your  note-book. 

Name    of    Pupil 

Xo.   of  sample Kind    of    Seed 


Weight   of    Pure    Seed Per  cent  of  pure  seed   

Weight    of    other    clover    and   grass  Per  cent  of  other  clover  and  grass 

seed    seed    

Weight   of    weed    seeds    Per  cent  of  weed  seed    

Weight   of    inert    material    Per  cent  of  inert  material 

Total    weight     

20.  Germination  of  Commercial  Seeds. — Count  100,  200, 
300,  400,  or  500  seeds  from  preceding  exercise.  Germinate 
these  seeds  between  sheets  of  wet  blotting  paper. 


PEPPER  AND  EGG-PLANTS  239 

21.  Weed  Seeds. — How  many  kinds  of  weed  seeds  did  you 
find  in  the  sample  used  in  exercise  for  purity  of  clover  'i  Do 
you  know  all  the  kinds  ? 

Heat  a  quantity  of  soil  long  enough  to  kill  all  seeds  in  it. 
If  you  are  in  doubt,  keep  the  soil  wet,  and  in  a  warm  place 
for  a  week.  If  any  growth  appears,  heat  it  a  second  time. 
Plant  your  weed  seeds  in  this  soil  and  see  if  you  can  recognize 
the  little  plants. 

22.  Grasses. — Repeat  the  preceding  exercise  for  grasses. 

23.  Potato  or  Tomato. — Describe  the  plant.  Make  a 
drawing  of  the  leaf.  How  are  the  leaves  arranged  on  the  stem  ? 
Where  are  the  flowers  located  ?    Are  they  single  or  in  groups  ? 

Make  drawing  or  diagram  showing  location  of  fiowers  and 
character  of  infiorescence.  Dissect  a  flower  and  make  draw- 
ings of  parts. 

How  many  sepals  ?  How  many  petals  ?  How  many  sta- 
mens ?  How  many  pistils  ?  Is  it  gamo-  or  poly-sepalous  ?  Is 
it  gamo-  or  poly-petalous  ? 

24.  Tomato  Fruit. — Examine  a  few  good  tomato  fruits. 
Can  you  find  the  calyx  ? 

Can  you  find  the  corolla  ? 

From  what  part  of  the  flower  is  the  fruit  developed  ? 
Do  potatoes   form   the  corresponding  part   of  the  flowei*? 
Why? 

How  many  seeds  in  a  single  tomato  ? 

25.  Potato  Tuber. — Examine  a  potato  tuber.  Is  the  tuber 
a  root  or  a  stem  ? 

What  are  the  eyes  of  the  potato  tuber  ? 

Cut  a  potato  tuber  so  that  some  of  the  pieces  will  have  eyes 
and  others  not.  Plant  and  watch  for  germination.  Will  they 
all  grow  ?    From  what  part  of  the  piece  do  the  sprouts  arise  ? 

26.  Pepper  and  egg-plants  may  be  studied  in  the  same  man- 
ner as  indicated  in  the  exercise  with  tomato  fruit. 


MO  SPECIAL  EXERCISES 

27.  Apple,  Pear  or  Quince. — Examine  an  apple  or  pear 
blossom.  How  many  sepals  'i  How  many  petals  'i  How  many 
stamens  (  How  many  pistils  '(  Is  it  gamo-  or  poly-sepalous  ( 
Is  it  gamo-  or  poly-petalous  ?  How  are  the  parts  attached  i 
What  is  the  position  of  the  ovary  ? 

28.  Peach,  Plum  or  Cherry. — Use  the  same  outline  as  in  the 
preceding  exercise. 

29.  Apple,  Pear  or  Quince  Fruits. — From  what  parts  of 
the  flower  is  the  apple,  pear  or  quince  developed  i 

Make  a  drawing  of  the  fruit. 

Cut  a  fruit  lengthwise,  make  drawing  and  label  all  parts. 
Cut  a  fruit  in  cross  section,  make  drawing  and  label  all 
parts. 

30.  Peach,  Plum  or  Cherry  Fruits. — Use  same  outline  as 
in  the  preceding  exercise. 

31.  Blackberry  or  Raspberry. — Compare  the  blossom  of  a 
blackberry  or  raspberry  with  the  blossom  of  the  apple  or  peach. 
How  does  it  resemble  and  how  does  it  ditter  from  the  blossom  of 
the  apple  or  peach  ? 

Make  a  series  of  drawings  showing  characters  of  the  flowers. 
Examine  a  berry.     From  what  part  or  parts  of  the  flower  is 
the  fruit  developed  ?    Make  a  series  of  drawings. 

32.  Strawberry. — Use  same  outline  as  in  the  preceding 
exercise. 

33.  Morning  Glory. — Dissect  the  flower  of  the  morning 
glory.  How  many  sepals  ?  How  many  petals  ?  How  many 
stamens  ?  How  many  pistils  ?  To  what  are  the  various  parts 
attached  ? 

Is  the  flower  gamo-  or  poly-sepalous  ?  Is  the  flower  gamo- 
or  poly-petalous  ? 

34.  Sweet  Potato. — The  sweet  potato  belongs  to  the  same 
family  as  the  morning  glory  and  the  flowers  are  'almost  the 
same.     The  sweet  potato  produces  an  abundance  of  blossoms 


COTTON  24] 

ill  tlio  tropical  countries,  but  in  the  temperate  cliiuates  it  sel- 
dom produces  blossoms. 

Is  the  edible  part  a  root  or  a  stem  ^  Compare  it  with  the 
edible  part  of  the  white  or  Irish  potato  ? 

35.  Cotton. — A  hollyhock  may  be  substituted  in  sections 
where  the  cotton  is  not  grown.  Study  the  plant.  Note  its 
shape,  length  of  interiiodes,  long  vegetative  and  short  flower 
branches  of  the  plant.     How  many  flowers  and  fruits  has  it  ? 

Study  the  flower,  and  make  a  series  of  drawings  to  show 
parts. 

Make  a  study  of  the  boll  of  the  cotton  or  seed-pod  of  the 
hollyhock. 


APPENDIX 

REFERENCES 

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242 


APPENDIX  243 

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Britton,  N.  L. :    ( 1 )   Manual  of  the  Flora  of  the  Nort(hem  States  and  Can- 
ada.    New  York:   Henry  Holt  &  Co.,  1901,  $2.25. 
(2)    North    American    Trees,     being    Descriptions    and     Hlustrations 

of  the   Trees   Growing  Independently   of   Cultivation   in   North 

America,  North  of  Mexico,  and /the  West  Indies.     New  York: 

Henry  Holt  &  Co.,  1908,  $7.00. 
Britton,    N.   L.,   and   Brown,   A. :      An   illustrated   Flora  of  ;the   Northern 
United  States,  Canada,  etc.     New  York:  Charles  Scribner's  Sons, 

3  vols.,  1896-1898,  $4.00  a  volume. 
Caldwell,  0.  W. :     Laboratory  Manual  of  Botany.    New  York:  D.  Appleton 

&  Co.,  1902,  GO  cents. 
Campbell,  D.   H.:      (4)   A  University  Text  Book  of  Botany.     New  Y^ork: 

The  Macmillan  Co.,  1902,  $4.00. 
Clark,  C.  H. :     A   Laboratory  Manual  of  Practical   Botany.      New  Y^ork: 

American  Book  Company,  1898,  96  cents. 
Clute,  W.  N.:      (1)    Our  Ferns  in  Their  Haunts,  a  Guide  to  all  the  Native 

Species.     New   York:    F.   A.   Stokes  Co.,   1901,  $2.00. 
(2)    The  Fern  Allies  of  North  America,  North  of  Mexico.     New  York: 

F.  A.   Stokes  Co.,    1905,  $2.00. 
Collins,  F.  S.:     Green  Alga;  of  the  United  Stated.     Tufts  College  Studies, 

1909,   $3.50. 
Conn,  H.  W. :      Bacteria,  Yeasts,  and  Molds  in  the  Home.     Boston:   Ginn 

&  Co.,  1903,  $1.20. 
Coulter,  J.  M. :      ( 1 )    Manual  of  the  Botany  of  the  Rocky  Mountain  Region. 

New  York:    American  Book  Co.,  1885,  $1.62. 
(2)    Plants,    a    Text-book    of    Botany     (combining    two    books.    Plant 

Relations    and    Plant    Structures).      New    York:    D.    Appleton 

&    Co..    1900.     Suggestions    for    teachers,    two    pamphets,    one 

by  O.  W.  Caldwell,  are  supplied  to  teachers  with  this  work,  $1.80. 
Gray,  Asa:      (2)   Field,  Forest  and   Garden   Botany.     Revised   by  L.   H. 

Bailey.     New  Y^'ork:   American  Book  Co.,  1868  and  later,  $1.44. 
(5)   Elements  of  Botany.     New  York:  American  Book  Co.,  1887  and 

later  editions,   94  cents. 


244  APPENDIX 

(8)  Manual  of  the  Botany  of  tlie  Nortliern  United  States.  Sixth 
Edition.  New  York:  American  Book  Co.,  18flO,  $1.02.  Field 
edition,  $2.00.     Seventh  edition,  by  Robinson,  B.  L. 

Green,  J.  R.:  (1)  An  Introduction  to  Vegetable  Physiology.  Philadelphia: 
P.  Blakiston's  Son  &  Co.,  1000  and  later,  .$3.00. 

Hilgard,  E.  W. :  Soils,  their  Formation,  Properties,  Composition  and 
Relations  to  Climate  and  Plant  Growth  in  the  Humid  and 
Arid  Regions.     New  York:  The  Macmillan  Co.,  1906,  $4.00. 

Hough,  R.  B.:  Handbook  of  the  TVees  of  the  Northern  States  and  Canada, 
East  of  the  Rocky  Mountains.  Photo-descriptive,  Lowville, 
N.  Y.:     Published  by  the  Author,   1907,  $8.00. 

Jackson,  B.  D. :  A  Glossary  of  Botianic  Terms  with  their  Derivation  and 
Accent.     Philadelphia:    J.  B.  Lippincott  &  Co.,  1900,  .$2.00. 

Kerner  van  Merilaun,  A.  Translated  by  F.  W.  Oliver:  Tlie  Natural  His- 
tory of  Plants.  New  Y'ork:  Henry  Holt  &  Co.,  4  vols.,  1894- 
1895,   $11.00. 

Kraemer,  Henry:  A  Text-book  of  Botany  and  Pharmacognosy  Intended 
for  the  use  of  students  of  Pharmacy,  as  a  Reference  Book  for 
Pharmacists,  and  as  a  Handbook  for  Food  and  Drug  Analysis. 
Philadelphia :.^J.  B.  Lippincott  Co.,  Third  Edition,   1908,  $5.00. 

Leavitt,  R.  G. :  Outlines  of  Botany  for  the  High  School  Laboratory  and 
Classroom  (based  on  Gray's  Lessons  in  Botany).  New  Y'ork: 
American  Book  Co.,  1901,  $1.00. 

MacDougal,  D.  T. :  ( 1 )  The  Nature  and  Work  of  Plants.  An  Introduction 
to  the  Study  of  Botany.  New  Y''ork:  The  Macmillan  Co.,  1900, 
80  cents. 

(2)  Practical    Text-book    of    Plant    Physiology.      New    York:     Long- 

mans, Green   &  Co.,   1901,   $3.00. 

(3)  Elementary   Plant  Physiolog}\     New  Y'ork:    Longmans,   Green   & 

Co.,    1902,   $1.20. 

Osterhout,  W.  J.  V.:  Experiments  with  Plants.  New  York:  The  Mac- 
millan Co.,  1905,  $1.25. 

Penhallow,  D.  P.:  A  Manual  of  the  North  American  Gymnosperms.  Bos- 
ton:   Ginn  &  Co.,   1907,  $4.50. 

Sargent,  C.  S.:  (2)  Manual  of  the  Trees  of  North  America  (exclusive  of 
Mexico).     Boston:   Houghton,  Mifflin  &  Co.,   1899,  75  cents. 

Small,  J.  K. :  Flora  of  the  Southeastern  United  States.  New  York :  Pub- 
lished by  the  Author  at  the  New  Y^ork  Botanical  Garden,  1903, 
$3.60. 

Stevens,  W.  C:  (2)  Plant  Anatomy,  from  the  standpoint  of  the  develop- 
ment and  functions  of  the  tissues,  and  handljook  of  micro- 
teehnie.     Philadelphia:    P.  Blakiston's  Son  &  Co.,   1907,  $2.00. 


APPENDIX  245 

Strasburger,  E.,  Noll,  F.,  Schenck,  H.,  and  Karsten,  G.,  Translated  by  W.  H. 
Lang:     A  Text-book  of  Botany.    New  York:  The  Macmillan  Co., 
1908,  $5.00. 
Underwood,  L.  M. :      (1)    Our  Native  Ferns  and  their  Allies.     New  York: 
Henry  Holt  &  Co.,   1881  and  later,  $1.00. 
(2)   Molds,    Mildews,    and    Mushrooms.      New    York:    Henry    Holt   & 
Co.,    1899,   $1.50. 
Vines,   S.    H. :     ( 1 )    Lectures   on   the    Physiology   of    Plants.      Cambridge : 
University  Press,   188G,   $5.00. 
(2)   Elementary   Text-book    of   Botany.      New   Y^ork:    The   Macmillan 
Co.,  1898,  $2.25. 
Waters,  C.  E.:      Ferns.     A  ISIanual  of  the  Northeastern  States.     New  Y^ork: 
Henry  Holt  &  Co.,  1903,  $3.00. 


GLOSSARY. 

Ac'au-les'cent.     Apparently  stenilpss. 

Ac-ces'so-ry.     Something  added.     Extra  organ  or  part. 

Ad-he'rent.     Growing  to  or  attached  to. 

Ad-he'sion.     The  union  of  organs  of  different  kinds,  as  stamens  to  petals, 

etc. 
Ad'nate.     Growing  fast  to;  united. 
Ad'ven-ti'tious.     Out  of  the  usual  order;  accidental. 
Ag'gre-gate.     Assembled  close  together. 
A-kene',  or  a-ken'ium,  or  a-chene'.     An  indehiscent  seed  vessel  or  fruit, 

hearing  one  seed. 
Al'ter-nate.      Distributed    singly    at    different   heights    of    the    stem;    not 

opposite. 
Am'ent.     A  catkin  type  of  inflorescence. 
Am'en-ta'ceous.     Catkin-like,  or  catkin-bearing. 
A-nal'y-sis   (botanical).     The  process  of  classifying  and  finding  the  names 

of  plants. 
A-nat'ro-pous.     Having  tiie  ovule  inverted  at  an  early  period  in  its  devel- 
opment, so  that  the  clialaza  is  at  the  apparent  apex. 
An'dre-ce'cium.    The  stamens  of  a  flower  taken  together. 
An'e-moph'i-lous.     Wind-loving;   said  of  wind-pollinated  flowers. 
An'gi-o-sperms.     Plants  whose  seeds  are  borne  in  a  closed  vessel. 
An'nu-al.     Yearly. 

An'nu-lar  cells.     Cells  with  ring-like  markings. 
An'ther.     The  part  of  the  stamen  that  contains  the  pollen. 
An'ther-id'i-um.    The  organ  in  cryptograms  corresponding  to  the  anther  in 

flowering  plants. 
A-pefal-ous.     Without  petals. 
A'pex.     The  to])  or  point,  especially  of  a  leaf. 
Ap'i-cal.     Belonging  to  the  apex  or  point. 
Ap-pend'age.     Any  superinduced  part. 
A-quat'ic.    Living  in  the  water. 
Ar'bo-re'tum.    A  collection  of  trees. 
Ar-bo're-ous.     Tree-like. 
Ar'che-go'ni-um.     The  organ  in  cryptograms;  corresponding  to  the  pistil  of 

flowering  plants. 
As-cend'ing,  or  as-cend'ent.    Arising  obliquely;  assurgent. 
As-sim'i-la'tion.    Tlie  function  of  producing  starch  or  other  plant  food. 
At'ro-pous,  or  at'ro-pal.     Not  inverted;  orthotropous. 

247 


248  GLOSSARY 

Awn   (on).     The  bristle  or  beard  of  barley  and  similar  plants. 

Ax'il.    The  angle  between  the  petiole  and  the  branch  on  the  upper  side. 

Ax'is.     The  stem  or  other  central  line  of  the  plant. 

Bac-te'ri-um,  Tlie  smallest  organism  known;  micro-orfjanisms,  destitute  of 
chlorophyll,  w'hich  multiply  with  great  rapidity  and  cause  putrefaction 
and  disease. 

Bast-cells.    Long  cells  of  bark. 

Beard'ed.     Having  tufts  of  long  hairs,  or  awns. 

Ber'ry.     A  fruit  with  a  fleshy  pericarp. 

Bi'col'or.    Two-colored. 

Bi-en'ni-al.     Of  two  years'  duration,  bearing  seeds  the  second  year  only. 

Bi-fo'li-ate.     With  two  leaflets. 

Bi-la'bi-ate.     Two-lipped. 

Bi'lobed.    Two-lobed. 

Bi-loc'u-lar.     Divided  into  two  cells. 

Bi-no'mi-al.     Having  two  names. 

Blade.     The  expanded  part  of  the  leaf. 

Bofa-ny.     The  science  which  treats  of  plants  and  plant  growth. 

Bract.  The  small  leaf  or  scale  from  the  axil  of  which  a  flower  or  its  pedicel 
proceeds. 

Branch.    A  shoot  growing  from  the  stem. 

Bry-oph'y-ta.     Moss  and  moss-like  plants. 

Bud  scales.     Coverings  of  a  bud. 

Bulb.     An  underground  bud. 

Bulb-if'er-ous.     Bearing  or  producing  bulbs. 

Bulb'lets.     Little  bulbs,  borne  above  ground. 

Ca-lyp'tra.     The  hood  of  the  spore-case  of  a  moss. 

Ca'lyx.     The  outer  floral  envelope. 

Cam'bi-um.    An  old  name  for  the  growing  cells  between  tlio  wood  and  hark  ; 

nascent  structure. 
Cam'py-lot'ro-pous.     Having  the  ovule  curved,   with   tiie  apex   near   the 

hiluin. 
Cap'il-la-ry,  or  cap-il-la'ceous.     Resembling  hair;   long  and  slender;  the 

passage  of  water  through  small  openings. 
Cap'i-tate.     Head-shapeil ;  growing  in  close  clusters  of  heads. 
Cap'sule.    A  dry  dehiscent  seed  vessel  with  more  than  one  carpel. 
Car'pel.    A  simple  pistil. 

Car'un-cle.    An  excrescence  near  the  liilum  of  some  seeds. 
Car'y-op'sis.    A  grain ;  a  thin,  dry,  one-seeded  pericarp. 
Cat'kin.     An  anient. 


GLOSSARY  249 

Cau'dex.     Tlie  trunk  or  stem  of  a  i)lant. 
Cau-les'cent.    Having  a  distinct  stem. 

Cau'li-cle.    A  little  stem,  or  rudimentary  stem  of  a  see<lling. 

Cau'line.    Relating  to  the  stem. 

Cell  growth.     Formation  and  enlfirgemcnt  of  cells. 

Cel'lu-lar  tis'sue.    Tissue  formed  of  cells. 

Cel'lu-lose.    The  substance  of  which  cell  walls  are  formed. 

Ce're-al.     Eelating  to  grains,  corn,  etc. 

Cha-la'za.     The  part  of  an  ovule  where  the  covering  and  nucellus  join. 

Chlo'ro-phyll.     The  green  substance  of  leaves  and  bark. 

Cir'cu-la'tion.     A  moving  around   (as  of  the  sap). 

Cla'vate.     Club-shaped. 

Cleis-tog'a-mous.     Pollination  in  closed  buds. 

Climb'ing.     Rising  by  clinging  to  other  objects  for  support. 

Com-plete'  flow'er.     One  that  has  all  the  organs — calyx,  corolla,  stamens 
and  pistils. 

Corn-pound'    flow'er.      One    composed    of   a   nuinl>er    cf   separate    flowers 
crowded  on  the  torus. 

Com-pound'  leaf.     Orte  composed  of  separate  leaflets,  or  little  leaves. 

Cone.    A  strobile,  a  multiple  fruit  having  the  shape  of  a  cone. 

Cork'y.     Of  the  texture  of  cork. 

Corm.     A  sort  of  bulb  or  fleshy  stem. 

Co-rol'la.     Inner  perianth  made  up  of  petals. 

Co-ro'na.     A  crown. 

Cor'ti-cal  bark.     Outer  bark. 

Cor'ymb.     A  flat-topped  or  convex  cluster  of  flowers,  each  on  its  own  foot- 
stalk, and  arising  from  difl"erent  points  of  a  common  axis. 

Cofy-le'dons.    Lobes  or  seed  leaves,  or  first  leaves  of  the  embryo. 

Creep'er.     A  plant  that  trails  on  the  ground. 

Cre'nate.     Bordered  with  round  teeth. 

Cross'-pol'li-na'tion.    The  pollination  of  a  plant  by  pollen  from  a  difl'erent 
individual. 

Cru'ci-form.    In  the  form  of  a  Roman  cross. 

Cryp'to-ga'mia.     Name  of  the  division  of  plants  witljout  flowers. 

Culm.    Tiie  straw  of  grasses. 

Cu'ne-ate,  or  cu-ne'i-form.    Wedge-shaped. 

Cu'pule.    A  little  cuj),  as  the  cup  of  the  acorn. 

Cus'pi-date.     Having  a  sharp,  stiflf  point. 

Cu'ti-cle.     Outer  lamina  of  wall  of  epidermis. 

Cyme.     Flower  cluster  Avith  the  oldest  flowers  at  the  to]>  or  centre. 


250  GLOSSARY 

De-cid'u-ous,     Fallin<i  at  the  ond  of  the  season. 

De-cum'bent.     Reclininjr  with  tlie  top  ascending. 

De-fo'li-a'tion.     The  casting  off  of  leaves. 

De-his'cent.     Opening  by  regular  valves. 

Del'i-ques'cent.     Branching,  so  that  the  stem  is  lost  in  branches. 

Del'toid.     Like  the  Greek  letter  ^  in  form. 

Den'droid.     Tree-like  in  form. 

Den'tate.    Toothed. 

De-nud'ed.     Become  naked. 

De-pend'ent.     Hanging  down. 

De-pressed.     Flattened  from  above;  low. 

De-scend'ing.     Tending  gradually  downward. 

Dex'trin.     A  gummy  substance  produced  by  the  action  of  diastase  upon 

starch. 
Di'a-del'phous.       Having     stamensi    grouped    into    two     sets     by     united 

rjaments. 
Di'ag-no'sis.     A  brief  statement  of  the  distinctive  character  of  a  plant  or 

group. 
Di-an'drous,    With  two  stamens. 

Di'a-stase.    A  peculiar  ferment  in  malt,  altering  starch  into  dextrin. 
Di-chla-myd'e-ous.     Having  both  calyx  and  corolla. 
Di-chot'o-mous.     Two  equal  forks. 

Di-cot'y-le'don-ous.     Having  two  cotyledons,  or  seed  lol)es. 
Di-cot'y-le'dons.    Plants  which  have  two  seed  leaves  in  their  embryos. 
Dif'fuse.     ^luch  divided  and  spreading. 
Dig'i-tate.     Having  several  distinct  leaflets  palmately  arranged,  as  in  tlie 

leaf  of  the  horse-chestnut. 
Di-mor'phous.     Having  two  forms. 
Di-oe'cious.     Having   staminate  and   pistillate   flowers  borne  on  different 

j)lants. 
Dru-pa'ceous.     Like  a  drupe. 
Drupe.     A  stone  fruit,  as  the  peach  and  cherry. 

El'a-ters.     Sjjiral,  elastic  tlireads  accompanying  certain  spores. 

El'lip-soi'dal.     Shaped  like  an  ellipsoid. 

El-lip'tic.     Having  the  form  of  an  ellipse. 

Em'bry-o.     The  young  plant  in  the  seed. 

Em'bry-o  sac.    The  cell  in  the  ovule  in  which  the  embryo  is  formed. 

En-dog'e-nous  struc'ture.     Structure  in  which  the  pith  and  woody  fibre 

are  indiscriminately  mingled. 
En'do-gens.     Plants  whose  structure  is  endogenous. 
En'do-sperm.     Tlie  food  immediately  surrounding  the  embryo. 


GLOSSARY  2£1 

En-tire'-mar'gined.     Havinji;  a  continuous  edge. 

En'to-moph'i-lous   (liovvers).     Frequented  and  pollinated  by  insects. 

E-phem'er-al.    Enduring-  for  one  day. 

Ep'i-carp.     The  outer  layer  of  a  seed  vessel. 

Ep'i-der'mis.    Outer  layer  of  cells. 

Es-sen'tial  or'gans   (of  a  flower).     Stamens  and  pistils, 

Ex'o-carp.     Outer  laj'er  of  a  pericarp. 

Ex-og'e-nous  struc'ture.     Structure  like  an  exogen. 

Fas'ci-cle.    A  bundle,  or  cluster. 

Feath'er-veined.     With  all  veins  from  the  sides  of  the  mid-no  or  Jiiu-vein. 

Fer'ti-li-za'tion.     Union  of  sex  cells. 

Fi'bro-vas'cu-lar.     Containing  woody  fibres  and  ducts. 

Fil'a-ment.     The  stalk  of  a  stamen. 

Fil'i-form.     Slender,  like  a  tliread. 

Flesh'y.     Composed  of  firm  pulp  or  flesh. 

Flo''ral  en've-lope.     Tlie  perianth  of  a  flower. 

Flow'er.     The  organ  whicli  produces  the  seed. 

Fo'li-ate.    Provided  with  leaves. 

FoI'Ii-cle.    A  one-celled,  many-seeded  carpel,  opening  by  the  ventral  suture. 

Fo-ra'men.     A  small  opening  or  orifice. 

Frond.    An  organ  which  is  both  stalk  and  leaf ;  usually  applied  to  ferns. 

Fruc'ti-fi-ca'tion.     The  act  of  producing  fruit. 

Fruit.     A  ripened  pistil;  a  seed  vessel  with  its  contents. 

Fru-tes'cent.     Shrubby  in  character. 

Fu'ni-cle,  fu-nic'u-lus.    The  stalk  of  an  ovule  or  seed. 

Fu'si-form.     Spindle-shaped. 

Gam'o-pefa-lous.     Having  the  petals  united;   sympetalous. 
Gam'o-sep'a-lous.    With  the  sepals  united. 
Gla'brous.     Smooth,  not  hairy. 
Glu-ma'ceous.     C41unie-like;  glume  bearing. 

Glumes.    Bracteal  coverings  of  flowers  or  of  the  seeds  of  grains  and  grasses. 
Grain,     The  gathered  seeds  of  cereal  plants, 

Gym'no-sper''mae.     A   class  of   exogenous  plants   characterized  by   naked 
seeds. 

Has'tate.      Triangular,   with   the   base   lobes   abruptly   spreading   as   in   a 

halberd. 
Heart'wood.    The  wood  near  the  central  part  of  an  exogenous  tree  or  shrub, 
Her-ba'ceous.    Green  and  cellular  in  texture. 
Her-maph'ro-dite    (flower).     Having  both  stamens  and  pistils. 


252  GLOSSARY 

Hef  er-og  a-mous.     Having  two  !*)rts  of  llowers  on  the  same  head. 

Hi'lum.     ihe  eye,  or  &car,  of  tlie  seed. 

Kir'sute.     Hairy;  with  rather  long  hairs. 

His'pid.     15ristly;  having  stiff  hairs. 

His-tol'0-gy.     The  science  of  cells  and  tissues. 

Hy'a-line.     Transparent,  or  nearly  so. 

Hy'brid.    A  cross  breed  between  two  species. 

Im-per'fect  flow'er.     A  fiower  wanting  either  stamens  or  pistils. 

In-com-plete'  fiow'er.     Wanting  calyx  or  corolla. 

In-cum'bent.      Having  the   radicle   lying  against  the  back   of  one  of  the 

cotyledons. 
In-def'i-nite.     Too  numerous  or  variable  for  specific  enumeration. 
In-def'i-nite    in'flo-res'cence,    or    in'de-ter'mi-nate    in'flo-res'cence.      A 

process  of  inflorescence  in   which  the  flowers  all   arise  from   axillary 

buds,  the  terminal  bud  continuing  to  grow,  and  extending  the   stein 

indGfinitely. 
In'de-his'cent.     Not  opening. 
In-dig'e-nous.     Native  to  a  country. 

In-du'si-um.     Tlie  shield  of  the  fruit  dots  (sori)   in  many  ferns. 
In'flo-res'cence.       IMode  of  flowering,  or  the  arrangement  of  flowers  on  a 

plant. 
In'nate.     Growing  on  the  top  of  the  part  that  sustains  it. 
In-sert'ed.     Situated  upon,  growing  out  of,  or  attached  to  some  part. 
In-teg'u-ment.     A  coat  or  covering. 

In'ter-cel'lu-lar   (passages,  spaces).     Lying  between  the  cells. 
In'ter-node.    The  space  between  two  nodes. 
Ir-reg'u-lar   flow'ers.      Flowers  whose  like  parts  differ  either   in  size  or 

shape. 

Key-fruit.    A  dry,  indehiscent,  usually  one-seeded,  winged  fruit ;  a  samara. 

Lac-tif'er-ous  tis'sue.     A  tissue  whose  cells  and  ducts  bear  milk-like  lluid. 
Leg'ume.    A  seed  vessel  which  opens  by  both  a  ventral  and  dorsal  opening, 

as  the  bean,  pea,  etc. 
Len'ti-cel.     A  small  oval  rounded  spot  upon  a  stem  or  branclii  from  which 

the  underlying  tissues  may  protrude. 
Loc'u-lar.     Relating  to  the  cell  or  compartiuent  of  an  ovary, 

Med'ul-la-ry  rays.     Rays  of  cellular  tissue  seen  in  a  transverse  section  of 
exogenous  wood  which  pass  from  the  pith  to  the  bark. 


GLOSSARY  253 

Mer'is-matic.     Dividiiij;  into  eolls  or  sof-meiits  by  the  formation  of  internal 

partitions;  i.  c,  the  formation  of  new  cells. 
Mes^o-carp.     The  middle  layer  of  a  pericarp,  consisting  of  three  distinct 

layers. 
Mi'cro-pyle.     An  opening  in  the  outer  coat  of  a  seed  through   which  the 

pollen  tnho  enters  the  ovule. 
Mid'-rib,  or  mid'-vein.     Tlie  central  vein  of  a  leaf. 

Mon'a-del'phous.     Having  the  stamens  united  iu  one  body  by  the  filaments. 
Mon'o-cot'y-le'don.     A  plant  having  only  one  cotyledon,  or  seed  leaf. 
Mo-noe'cious.     Having  stamens  and  pistils  on  the  same  plant. 
Mon'o-pet'al-ous.     Having  but  one  petal. 
Mor-phol'o-gy.     'I'iiat  branch  of  biology  which  deals  with  the  structure  of 

animals  and  plants,  and  treats  of  the  lonns  of  organs,  describing  tiieir 

homologies. 
My-ce'li-um.     Tlie  white  threads  of  filamentous  growth  of  a  fungus. 

No'men-cla'ture.     The  technical  names  used   in  any  particular  branch  of 

science  or  art. 
Nu-cel'lus.     The  essential  Iwdy  of  an  ovule  wliere  the  embryo  is  developed. 
Nu-cle'o-lus.     A  dense  rounded  body  within  a  nucleus. 
Nu'cle-us.     A  dense  body  within  the  protoplasm  of  a  cell. 

Ob-cor'date.     Heart  shaped,  with  tlie  attachment  at  the  pointed  end. 
Ob-Ian'ce-o-late,     Lanceolate^  narrowing  toward  the  point  of  attachment. 
Or'gan.     Any  member  of  a  plant,  as  a  leaf,  a  stamen,  etc. 
O'vule.     The  young  seed. 

Pa'lea.     Chaff,  or  chaff-like  bract. 

Pal'et.     Same  as  palea. 

Pal'mate.     Lobed  so  that  the  sinuses  point  to  the  apex. 

Pan'i-cle.     A  branching  raceme. 

Pa-pil'i-o-na'ceous.     Resembling  the  butterfly,  as  in  some  of  the  legumes. 

Pap'pus.     The  awns,  or  bristles,  which  represent  the  calyx  in  conipositu'. 

Par'al-lel-vein'ed.     Having  the  veins  or  nerves  extending  from  the  base  of 

t]u>  leaf  to  the  apex,  parallel  to  the  midvein. 
Pa-raph'y-sis.      A    minute-jointed    filament    among    the    arcliegonia    and 

antheridia  of  mosses. 
Par'a-site.    A  jilant  obtaining  noiirishiuent  inimediately  fi-om  aiiotlier  ])lant 

to  which  it  attaches  itself. 
Pa-ren'chy-ma.   Soft  cellular  plant  tissue,  like  the  pulp  of  leaves,  having  no 

wood  fibre. 
Pa-ri'e-tal.     Attached  to  tlie  nuiin  wall  of  the  ovarv. 


254  GLOSSARY 

Per-en'ni-al.     Living  sevpral  years. 

Per'fect  flow'er.     A  flower  having  lx)tli  stamens  and  pistils. 
Per'i-anth.    Calyx  or  corolla,  or  both;  the  leafy  parts  of  a  flower  surround- 
ing the  stamens  and  pistils. 
Per'i-carp.     The  ripened  ovary ;  the  covering  of  the  seed. 
Pet'al.     Part  of  the  corolla. 

Pet'i-ole.     The  stalk  of  a  leaf  connecting  the  leaf  with  the  stem. 
Phae'no-ga'mia,   or   pha-ne-ro-ga'mi-a.      Name   of   that   division    of    the 

vegetable  kingdom  which  bears  visible  flowers. 
Pis'til.     Organ  of  a  flower,  made  up  of  ovary,  style  and  stigma,  or  ovary 

and  stigma. 
Pith.    The  soft  tissue  in  the  centre  of  the  stems  of  dicotyledonous  plants. 
Pla-cen'ta.     The  part  of  a  pistil  or  fruit  to  which  the  ovules,  or  seeds,  are 

attached. 
Plu'mule.     The  first  bud  of  the  embryo  plant. 
Pod.     A  capsule,  especially  a  legume. 
Pol'len.     The  fructifying  cells  Ixjrne  in  the  anthers. 
Pol'len  tube.     The  slender  tube  sent  down   from  the  pollen  through  the 

style  of  the  pistil  to  the  ovum  in  the  ovule. 
Pol'li-na'tion.     The  act  of  transferring  pollen  to  the  stigma. 
Pol'y-cofy-le'don-ous.     Having  many   (more  than  two)   cotyledons,  as  in 

tlie  i)ines. 
Pol'y-pet'a-lous.     Having  the  petals  separate  from  each  other. 
Pol'y-sep'a-lous.     Having  the  sepals  separate  from  each  other. 
Pome.     A  fruit  like  an  apple. 
Pro-cum'bent.     Trailing,  prostrate. 
Pro-thal'li-um,  pro-thal'lus.     The  minute  primary  growth  from  the  spore 

of  ferns  which  bears  the  true  sexual  organs. 
Pro'to-plasm.     The  primary  organic  substance  of  the  cell. 
Pseu'do.     False. 

Pter'i-do-phytes'.     Ferns  and  fern-like  plants. 
Pu-bes'cent.     Covered  with  fine  short  hairs. 

Ra-ceme'.     A  flower  cluster  with  an  elongated  axis  and  many  one-flowered 

lateral  pedicels. 
Ra'chis,  or  rha'chis.     The  principal   axis  in  a  spike,  raceme,  panicle  or 

corymb. 
Rad'i-cle.     Tlie  rudimentary  stem  of  a  plant  which  supports  the  cotyledons 

in  the  seed,  and  from  which  the  root  is  developed  downward;  a  rootlet. 
Ra'phe.     The  continuation  of  the  seed  stalk  along  the  side  of  an  anatropous 

ovule  or  seed,  forming  a  ridge  or  seam. 


GLOSSARY  255 

Re-cep'ta-cle.  Tlie  apex  of  the  flower  stalk,  fiom  which  the  organs  of  the 
flower  grow. 

Reg'u-lar.     Having  all  the  parts  of  the  same  kind  alike  in  size  and  shape. 

Res'pi-ra'tion.  Breathing;  the  absorption  by  plants  of  oxygen;  the  oxida- 
tion of  assimilated  products,  and  the  release  of  carbon  dioxide  and 
watery  vapor. 

Rha'chis.    The  axis  of  a  spike  inflorescence. 

Rha'phe.  The  continuation  of  the  seed  stalk  along  the  side  of  an  anatropous 
ovule  or  seed,  forming  a  ridge  or  seam. 

Rhi^zome.     An  underground  stem. 

Root.  The  descending  axis  of  a  plant;  the  part  of  a  plant  that  grows  down- 
ward into  the  ground.     It  bears  no  true  buds. 

Root'  cap.  A  mass  of  dead  cells  which  cover  and  protect  the  growing  cells 
at  the  end  of  a  root. 

Root'  stock.     Same  as  rhizome. 

Sag'it-tate.     Arrow  shaped. 

Sam'a-ra.     Indehiscent,  winged  fruit. 

Sap.    The  watery  fluid  taken  up  by  the  root,  and  moved  through  the  vessel 

up  to  the  leaves. 
Sap'  wood.     The  last  growth  of  wood  in  an  exogen. 
Seed.    Matured  ovule. 
Se'pal,    One  of  the  parts  of  the  calyx. 
Ses'sile.    Without  stean. 
Sol'i-ta-ry.     Growing  alone  or  singly. 
So'rus.     A  fruit  dot  of  ferns. 
Spa'dix.    A  spike  with  a  fleshy  axis. 

Spathe.    A  large  bract,  or  a  pair  of  bracts,  inclosing  a  flower  cluster. 
Spike.     An  inflorescence  in  which  the  flowers'  are  sessile  on  a  lengthened 

axis. 
Spo-ran'gi-um.    A  spore  case  in  cryptogamous  plants. 
Spore.     A  reproductive  grain  in  flowerless  plants,  analogous  to  a  seed  in 

flowering  plants. 
Sta'mens.     The   organs   that   produce   pollen,   consisting   of   fllament   and 

anther. 
Sto'lon.    A  branch  at  the  base  of  a  plant  which  roots  easily. 
Sto'ma.     One  of  the  openings  in  the  epidermis  of  a  leaf;  a  breathing  pore. 
Style.    That  part  of  the  pistil  between  the  ovary  and  the  stigma. 
Su-pe'ri-or.    Above  the  ovary. 
Su-pe'ri-or  o'va-ry.     Ovary  free  from  calyx. 
Sym-pet'al-ous.     Having  the  petals  united;  gamoix'talous. 


256  GLOSSARY 

Thal'lus.    A  mass  of  cellular  tissue,  usually  in  the  form  of  a  flat  stratum  or 

expansion,  instead  of  stem  and  leaves. 
Tri'chome.    A  hair  on  the  surface  of  a  leaf  or  stem,  or  any  modification  of 

a  hair. 
Tu'ber.     A  fleshy  underground  stem,  or  branch,  with  buds. 

Um'bel.     An  inflorescence  in  which  the  pedicels  all  spring  from  the  same 
point,  like  the  ribs  of  art  umbrella. 

Veins.    The  system  of  branching  vascular  woody  tissue  seen  in  leaves. 

Xy'lem.    That  portion  of  a  fibro-vascular  bundle  developed  into  wood  cells. 

Zo'o-spore.    A  spore  provided  with  one  or  more  slender  cilia,  by  the  vibra- 
tion of  which  it  swims  in  the  water. 


INDEX 


Aceraceae,  198 

Acids,  108 

Agriculture,  earliest  records,  183 

history  of,   184 
Alkaloids,  108 
Algae,   169 
Almond,  206 
Althea,  193 
Anatomy,  93     • 
Annuals,  23 

Annular  rings,  31,  99,  100 
Anther,  61 

Antheridiiun,  161,   165,  167,  171 
Apetalous,  56 
Apium,  215 
Apple,  205,  240 

Archegonium,  160,  101,  105,  167 
Asparagus,  228 
Avena,  230 

Bacteria,  117,  169,  177 

Banana,  227 

Barley,  230 

Bean,  6,  14,  202,  237 

Beets,  222 

Berries,  206-208,  217,  235,  240 

Biennials,  23 

Blade  of  leaf,  48 

Brassiea,  185 

Bread  mold,   172 

Breeding  of  plants,  147 

Broom  corn,  232 

Bryales,   166 

Bryophytes,   164 

Buckwheat,  222 

Budding,  39 

Bud  scales,  51 

Buds,  31,  40,  41 

Bundles,  fibro-vascular,  97,  100 


Cabbage,  185 
Calyptra,  164 
Calyx,  54 

modifications   of,    60 
Cambium,  31,  97 
Cannabis,  225 
Carrot,  215 
Capsicum,  220 
Capsule,  164 
Carbohydrates,   107 

formation  of,  115 
Caruncle,  7,  12 
Castanea,  227 
Castor  bean,  7,  14 
Ca,tkin,  65 
Celery,  215 
Cells,  93,  98 
Cellulose,    107 
Chemical   composition,   105 
Chenopodiaeeae,  221 
Cherry,  206,  240 
Chestnut,  227 
Chlorophyll,   46 
Cinchona,  215 
Circulation,  118 
Citrus,  190 
Classification,   65,   70 
Clover,  200,  203,  238 
Cocoa,   193 
Coffee,  215 
Compositae,  216,  235 
Cones,  122 
Convolvulaceae,  218 
Com,  6,  15,  231,  236 
Corolla,  54,  60 
Corylus,  227 
Corymb,  64 
Cotton,  191,  241 
Cotyledons,  4.  5,  10,  16 

257 


258 


INDEX 


Cruciferea,  185 
Cryjitogams,.  70 
Cucurbitacete,  211,  235 
Cupulifeiae,  22G 
Currants,  211,  235 
Cycadales,  124 
Cyme,  G5 

Daucus,  215 

Deciduous,  122 

Dicotyledons,  4,  70 

Dioecious,  58 

Dioscoraecese,  218 

Diseases  of  plants,  139,  141,  177 

Ecological  relations,  126 
Egg,  76 
Eggplant,  239 
Elaters,  168 
Elm,  224 

Embryo,  3,  5,  76,  83 
Endogenous,  31,  71 
Energy,  111 
Epicotyl,  7 
Epigynous,  63 
Equisetum,   161 
Exogenous,  31,  71 
Exosmosis,  113 
Evergreens,   121 

Fagopyrum,  222 

Fats,  107 

Ferna,   158 

Fertilization,  75,  76,  123 

Fertilizers,   130 

Fibrovascular  bundles,  97 

Ficus,  225 

Filaments,  61 

Flax,  193 

Flowers,  54,  57,  58,  64,  65,  75 

Foliage,  first,  10 

Foods,  5,  19,  22,  111 


Forestry,  134 
Fruits,  83 
Fungi,  169     • 

Gamopetalous,  60 

Galls,  142 

Gas,   formation  of,   16,   115 

Geography,  131 

Geotropism,  18 

Germination,  12,  15 

Goosefoot,   221 

Gossypium,  191 

Gourd,  213 

Grafting,  39 

Graminete,  228 

Grape,  197 

Grass,  228,  239 

Growth,   41,  42 

Gumbo,  191 

GjTiinosperms,  70,  121 

Halophyte,  128 
H'austoria,  24 
Hazelnut,  227 
Head,  65 
Heart  wood,  100 
Heat,  15 
Heath,  217 
Hemp,  225 
Hepaticea;,  164,  166 
Hibiscus,    191 
Hickories,  225,  235 
Hilum,  7,  12 
Hollyhock,  193 
Hop,  225 
Horsetail,  161 
Hordeum,  230 
Humulus,  225 
Humus,  117 
Hybridization,  148 
Hydrocarbons,  107 
Hydrophyte,  127 


INDEX 


259 


Hypocotyl,  7 
Hypogynous,  63 

Indusiuni,  159 
Inflorescence,   64 
Iponioese,  218 

Juglandaceae,   225 

Lamella   of   leaf,   48 

Leaves,  4,  45,  48-51,  93,  102,  131, 

142,  159 
Leguminoseae,  199 
Light,  15,  45 
LiliaceiB,  228,  232 
Linaceffi,   193 
Linum,  193 
Liverwort,   164,  166 
Lycopersicuni,  220 

Madder,  215 
Mallow,  191 
Malvaceae,   191 
Maple,  198,  234 
Marchantia,  166 
Medullary  rays,  99 
Melons,  213 
Mesopliyte,    128 
Micropyle,  7 
Microsporangia,   123 
Midrib,  48 
Millet,   230 
Minerals,  116 
Moisture,  9,  12.  15,  19 
Mould,  172 

Monocotyledonous,  4,  70 
Morning  glory,  240 
Morus,  223 
Mosses,  164 
Mulberry,  223 
Musca,  227 
Musci,  164 
Mustards,  185,   186,  234 


Mutation,  147 
Myoetozoa,  178 
Myxoniycetes,   178 

Nettle,  223 
Nicotiana,  220 
Nightshade,  219 
Nitrogen,   116,   117,  129 

Oak,  226,  235 
Oats,  230,  237 
(Edogonium,  171 
Oils,  107,  108 
Okra,  191 
Onion,  228 

Operculum,  164 
Orange,  196 
Organic  acids.  108 
Oryza,  230 
Osmosis.  29,  112 
Ovary.  62,  63 
Ovum,  76 
Ovules,  62,  83 
Ox.ygen,  9 

Parenchyma,  99 
Parsley,  215 
Parsnip,  215 
Pastinaca,  215 
Pea,   199,  203.  237 
Peach,  205,  240 
Peanut,  203     . 
Pear,  205,  240 
Pepper,  220.  239 
Perennials.  23 
Perianth,  55 
Perigynous,  63 
Peristome,  164 
Petal,  54 
Petiole.  48 
Pliloom,  08 


260 


INDEX 


Photosynthesis,  46 
Pistil,  54,  02 
Placenta,  63 
Plant  breeding,  147 

diseases,  139 

foods,  111 

geography,  131 

hair,  103 

societies,  147 
Plants,  composition  of,  105 

uses  of,  183 
Plum,  240 
Plumule,  14 
Pollen,  02,  123 
Pollination,  75,  79,  80,  122 
Polygonaceous,  222 
Polypetalous,  GO 
Populous,  227 
Potato,  219 

sweet,  218,  240 
Proteins,  108,  110 
Prothallus,  160,  164 
Protonema,  164 
Protoplasm,  93 
Pteridophytes,  158 
Pyrus,  205 

Quercus,   226 
Quince,  240 
Quinine,  215 

Raceme,  64 
Radicle,  7,  12 
Radish,  189,  234 
Raphe,  7 

Rays,  medullary,  99 
Reproduction,  74 

of  ferns,  100 
Respiration,  51 
Rheum,  222 
Rhizome,  37 
Rhizopus  nijrricans,  172 


Rhubarb,  222 

Ribs  of  leaves,  48 

Rice,  230 

Rings,  annular,  32,  99.  100 

Roots,    4,    18,    20,   23-25,   27-30, 

101 
Root  hair,  25,  26 
Rosacete,  204 
Rose,  204 
Rootstock,  37 
Rubiacese,  215 
Rue,  195 
Rutacete,   195 

Saccharum,  232 

Saccharomyces,   172 

Salicacese,  227 

Salix,  227 

Saprolegnia,  173 

Sapwood,  100 

Saxifragaceae,  211 

Saxifrage,  211 

Scales  of  buds,  51 

Scutellum,  11 

Secale,   230 

Seeds,  3,  4,  7,  75,  77,  78,  83,  88^ 

89,  137,  239 
Seedling,  3 
Sepal,  54 
Setaria,  230 
Seieties  of  plants,  127 
Soil,  128,   129 
Solanceae,  219 
Solanum,  219 
Sorghum,  232 
Sori,   159 
Spadix,  65 
Sperms,  171 
Sphagnales,    166 
Spike,  65 
Spinach,  222 
Spirogyra,  94,  170 


INDEX 


261 


Sporangium,  IGO,  173 

Si>orop.hyll,   1G2 

Sprouting,  7,  10 

Stamen,  54,  01,  123 

Starch,   lOG 

Stems,  4,   31-33,   35,   38,   47,  93, 

98,  121 
Sterculia,  193 
Sterculiaceae,    193 
Stigma,  62 
Stomata,  38 
Style,  62 

Sugar,  107,   116,  232 
Sunflower,  216 
Sunlight,  40 
Sweet  potato,  218,  240 

Tannins,  108 
Temperature,  130 
Thallophytes,  169 
Theobroma,    193 
Tobacco,  220 
Tomato,   220,  239 
Torus,  54 

Transpiration,  113,   114 
Trees,  135-137 
Trichomes,  25,  103 
Triticiun,  229 
Tropophyte,   128 
Turnips,  188 

Ulmus,  224 
Ulothrix,  171 


Umbel,  05 
Umbillifera',  215 
Urticaceae,  223 
Uses   of  plants,    183 

Vacciniaceae,  217 
Variations,   147 
Vaucheria,  171 
Veins,  48 
Vine,  196 
Violaceae,  189 
Violet,  189 
Vitaceae,  196 
Vitis,  197 

Walnut,  225,  235 

Warmth,  8 

Water,  15,  16,  105,  112,  114,  120 

Weeds,   150,  239 

Wheat,  229,  237 

Willow,  227,  230 

Wood,  100 

Xerophytes,   128 
Xylem,  98 

Yam,  218 
Yeast,  172 

Zea,  231 

Zingibracea;,    227 
Zoospores,   171 
Zygospores,   171 


nOeERTY  UBRAHY 

V.  C.  State  Colkge 


